organic/src/wasm_test/compare.rs

use std::borrow::Borrow;
use std::borrow::Cow;
use std::collections::BTreeSet;
use std::collections::HashMap;

use super::diff::WasmDiffResult;
use super::diff::WasmDiffStatus;
use crate::util::elisp::maybe_token_to_usize;
use crate::util::elisp::unquote;
use crate::util::elisp::EmacsStandardProperties;
use crate::util::elisp::TextWithProperties;
use crate::util::elisp::Token;
use crate::wasm::WasmAstNodeWrapper;
use crate::wasm::WasmDocument;

pub fn wasm_compare_document<'s>(
    source: &'s str,
    emacs: &Token<'s>,
    wasm: &WasmAstNodeWrapper<WasmDocument>,
) -> Result<WasmDiffResult<'s>, Box<dyn std::error::Error>> {
    let wasm_json = serde_json::to_string(&wasm)?;
    let wasm_json_parsed = serde_json::from_str(&wasm_json)?;
    compare_json_value(source, emacs, &wasm_json_parsed)
}

fn compare_json_value<'s>(
    source: &'s str,
    emacs: &Token<'s>,
    wasm: &serde_json::Value,
) -> Result<WasmDiffResult<'s>, Box<dyn std::error::Error>> {
    // println!("XXXXXXXXXXXXXX compare_json_value XXXXXXXXXXXXXX");
    // println!("{:?}", emacs);
    // println!("{:?}", wasm);
    // println!("XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX");
    match (wasm, emacs) {
        (serde_json::Value::Object(wasm), Token::List(el)) if wasm.contains_key("ast-node") => {
            // We hit a regular ast node.
            compare_ast_node(source, el, wasm)
        }
        (serde_json::Value::String(w), Token::Atom(e))
            if e.starts_with('"') && e.ends_with('"') =>
        {
            // We hit a string compared against a quoted string from elisp (as opposed to an unquoted literal).
            compare_quoted_string(source, e, w)
        }
        (serde_json::Value::Array(w), Token::List(e)) => {
            // TODO: This is creating children with no names.
            wasm_compare_list(source, e.iter(), w.iter())
        }
        (serde_json::Value::Object(wasm), Token::List(e))
            if wasm.contains_key("optval") && wasm.contains_key("val") =>
        {
            compare_optional_pair(source, e, wasm)
        }
        (serde_json::Value::Object(wasm), Token::List(el)) if wasm.contains_key("object-tree") => {
            // We hit an object tree additional property.
            compare_object_tree(source, el, wasm)
        }
        (serde_json::Value::Object(wasm), Token::List(el)) if wasm.contains_key("number-lines") => {
            // We hit an object tree additional property.
            compare_number_lines(source, el, wasm)
        }
        (serde_json::Value::Object(wasm), Token::List(el)) if wasm.contains_key("string-set") => {
            // We hit an object tree additional property.
            compare_string_set(source, el, wasm)
        }
        (serde_json::Value::Object(w), Token::TextWithProperties(e)) if is_plain_text(w) => {
            compare_plain_text(source, e, w)
        }
        (serde_json::Value::Null, Token::Atom("nil")) => Ok(WasmDiffResult::default()),
        (serde_json::Value::Bool(false), Token::Atom("nil")) => Ok(WasmDiffResult::default()),
        (serde_json::Value::Bool(true), Token::Atom(e)) if (*e) != "nil" => {
            Ok(WasmDiffResult::default())
        }
        (serde_json::Value::Bool(w), Token::Atom(e)) => {
            let mut result = WasmDiffResult::default();
            result.status.push(WasmDiffStatus::Bad(
                format!(
                    "Value mismatch. Emacs=({emacs:?}) Wasm=({wasm:?}).",
                    emacs = e,
                    wasm = w,
                )
                .into(),
            ));
            Ok(result)
        }
        (serde_json::Value::Number(w), Token::Atom(e)) if w.to_string().as_str() == (*e) => {
            Ok(WasmDiffResult::default())
        }
        (serde_json::Value::Number(w), Token::Atom(e)) => {
            let mut result = WasmDiffResult::default();
            result.status.push(WasmDiffStatus::Bad(
                format!(
                    "Value mismatch. Emacs=({emacs:?}) Wasm=({wasm:?}).",
                    emacs = e,
                    wasm = w,
                )
                .into(),
            ));
            Ok(result)
        }
        (serde_json::Value::Array(w), Token::Atom("nil")) if w.is_empty() => {
            Ok(WasmDiffResult::default())
        }
        (serde_json::Value::String(w), Token::Atom(e)) if w.as_str() == *e => {
            Ok(WasmDiffResult::default())
        }
        (serde_json::Value::Object(w), _) if w.contains_key("noop") => {
            Ok(WasmDiffResult::default())
        }
        (serde_json::Value::Null, Token::Atom(_)) => todo!(),
        (serde_json::Value::Null, Token::List(_)) => todo!(),
        (serde_json::Value::Null, Token::TextWithProperties(_)) => todo!(),
        (serde_json::Value::Null, Token::Vector(_)) => todo!(),
        // (serde_json::Value::Bool(_), Token::Atom(_)) => todo!(),
        (serde_json::Value::Bool(_), Token::List(_)) => todo!(),
        (serde_json::Value::Bool(_), Token::TextWithProperties(_)) => todo!(),
        (serde_json::Value::Bool(_), Token::Vector(_)) => todo!(),
        // (serde_json::Value::Number(_), Token::Atom(_)) => todo!(),
        (serde_json::Value::Number(_), Token::List(_)) => todo!(),
        (serde_json::Value::Number(_), Token::TextWithProperties(_)) => todo!(),
        (serde_json::Value::Number(_), Token::Vector(_)) => todo!(),
        // (serde_json::Value::String(_), Token::Atom(_)) => todo!(),
        (serde_json::Value::String(w), Token::Atom(e)) => {
            let mut result = WasmDiffResult::default();
            result.status.push(WasmDiffStatus::Bad(
                format!(
                    "Value mismatch. Emacs=({emacs:?}) Wasm=({wasm:?}).",
                    emacs = e,
                    wasm = w,
                )
                .into(),
            ));
            Ok(result)
        }
        (serde_json::Value::String(_), Token::List(_)) => todo!(),
        (serde_json::Value::String(_), Token::TextWithProperties(_)) => todo!(),
        (serde_json::Value::String(_), Token::Vector(_)) => todo!(),
        (serde_json::Value::Array(_), Token::Atom(_)) => todo!(),
        // (serde_json::Value::Array(_), Token::List(_)) => todo!(),
        (serde_json::Value::Array(_), Token::TextWithProperties(_)) => todo!(),
        (serde_json::Value::Array(_), Token::Vector(_)) => todo!(),
        (serde_json::Value::Object(_), Token::Atom(_)) => todo!(),
        (serde_json::Value::Object(_), Token::List(_)) => todo!(),
        (serde_json::Value::Object(_), Token::TextWithProperties(_)) => todo!(),
        (serde_json::Value::Object(_), Token::Vector(_)) => todo!(),
    }
}

fn compare_optional_json_value<'s>(
    source: &'s str,
    emacs: Option<&Token<'s>>,
    wasm: Option<&serde_json::Value>,
) -> Result<WasmDiffResult<'s>, Box<dyn std::error::Error>> {
    match (emacs, wasm) {
        (None, None) | (None, Some(serde_json::Value::Null)) | (Some(Token::Atom("nil")), None) => {
            Ok(WasmDiffResult::default())
        }
        (None, Some(serde_json::Value::Object(w))) if w.contains_key("noop") => {
            Ok(WasmDiffResult::default())
        }
        (Some(e), Some(w)) => compare_json_value(source, e, w),
        _ => Ok(WasmDiffResult {
            status: vec![WasmDiffStatus::Bad(
                format!(
                    "Nullness mismatch. Emacs=({emacs:?}) Wasm=({wasm:?}).",
                    emacs = emacs,
                    wasm = wasm
                )
                .into(),
            )],
            children: Vec::new(),
            name: "".into(),
        }),
    }
}

fn compare_ast_node<'s>(
    source: &'s str,
    emacs: &[Token<'s>],
    wasm: &serde_json::Map<String, serde_json::Value>,
) -> Result<WasmDiffResult<'s>, Box<dyn std::error::Error>> {
    let mut result = WasmDiffResult::default();
    let mut emacs_list_iter = emacs.iter();

    {
        // Compare ast node type.
        let emacs_name = emacs_list_iter
            .next()
            .ok_or("Should have a name as the first child.")?
            .as_atom()?;
        let wasm_name = wasm
            .get("ast-node")
            .ok_or("Should have a ast node type.")?
            .as_str()
            .ok_or("Ast node type should be a string.")?;
        result.name = emacs_name.into();
        if emacs_name != wasm_name {
            result.status.push(WasmDiffStatus::Bad(
                format!(
                    "AST node name mismatch. Emacs=({emacs}) Wasm=({wasm}).",
                    emacs = emacs_name,
                    wasm = wasm_name,
                )
                .into(),
            ));
        }
    }

    if result.is_bad() {
        return Ok(result);
    }

    let emacs_attributes_map = emacs_list_iter
        .next()
        .ok_or("Should have an attributes child.")?
        .as_map()?;
    let wasm_attributes_map = wasm
        .get("properties")
        .ok_or(r#"Wasm ast node should have a "properties" attribute."#)?
        .as_object()
        .ok_or(r#"Wasm ast node "properties" attribute should be an object."#)?;

    {
        // Compare attribute names.
        let emacs_keys: std::collections::BTreeSet<String> = emacs_attributes_map
            .keys()
            .map(|s| (*s).to_owned())
            .collect();
        // wasm_attributes_map.iter().filter_map(|(k,v)| if matches!(v, serde_json::Value::Null) {None} else {Some(k)}).map(wasm_key_to_emacs_key)
        let wasm_keys: std::collections::BTreeSet<String> =
            std::iter::once(":standard-properties".to_owned())
                .chain(wasm_attributes_map.keys().map(wasm_key_to_emacs_key))
                .collect();
        let emacs_only_attributes: Vec<&String> = emacs_keys.difference(&wasm_keys).collect();
        let wasm_only_attributes: Vec<&String> = wasm_keys
            .difference(&emacs_keys)
            .filter(|attribute| {
                emacs_attributes_map
                    .get(attribute.as_str())
                    .map(|token| !matches!(token, Token::Atom("nil")))
                    .unwrap_or(false)
            })
            .collect();
        if !emacs_only_attributes.is_empty() {
            result.status.push(WasmDiffStatus::Bad(
                format!(
                    "Wasm node lacked field present in elisp node ({name}).",
                    name = emacs_only_attributes
                        .iter()
                        .map(|s| s.as_str())
                        .intersperse(", ")
                        .collect::<String>(),
                )
                .into(),
            ));
        }
        if !wasm_only_attributes.is_empty() {
            result.status.push(WasmDiffStatus::Bad(
                format!(
                    "Elisp node lacked field present in wasm node ({name}).",
                    name = wasm_only_attributes
                        .iter()
                        .map(|s| s.as_str())
                        .intersperse(", ")
                        .collect::<String>(),
                )
                .into(),
            ));
        }
    }

    if result.is_bad() {
        return Ok(result);
    }

    {
        // Compare attributes.
        for attribute_name in wasm_attributes_map.keys() {
            let mut layer = WasmDiffResult::<'_> {
                name: Cow::Owned(attribute_name.clone()),
                ..Default::default()
            };
            let wasm_attribute_value = wasm_attributes_map.get(attribute_name);
            let emacs_key = wasm_key_to_emacs_key(attribute_name);
            let emacs_attribute_value = emacs_attributes_map.get(emacs_key.as_str()).copied();
            let inner_layer =
                compare_optional_json_value(source, emacs_attribute_value, wasm_attribute_value)?;
            if !inner_layer.name.is_empty() {
                layer.children.push(inner_layer);
            } else {
                layer.extend(inner_layer)?;
            }
            result.children.push(layer);
        }
    }

    {
        // Compare standard-properties.
        let mut layer = WasmDiffResult::<'_> {
            name: "standard-properties".into(),
            ..Default::default()
        };
        let emacs_standard_properties = wasm_get_emacs_standard_properties(&emacs_attributes_map)?;
        let wasm_standard_properties = wasm
            .get("standard-properties")
            .ok_or(r#"Wasm AST nodes should have a "standard-properties" attribute."#)?
            .as_object()
            .ok_or(r#"Wasm ast node "standard-properties" attribute should be an object."#)?;
        for (emacs_value, wasm_name) in [
            (emacs_standard_properties.begin, "begin"),
            (emacs_standard_properties.end, "end"),
            (emacs_standard_properties.contents_begin, "contents-begin"),
            (emacs_standard_properties.contents_end, "contents-end"),
            (emacs_standard_properties.post_blank, "post-blank"),
        ] {
            match (emacs_value, wasm_standard_properties.get(wasm_name)) {
                (None, None) | (None, Some(serde_json::Value::Null)) => {}
                (None, Some(_)) => {
                    layer.status.push(WasmDiffStatus::Bad(
                        format!(
                            "Elisp node lacked field present in wasm node. Name=({name}).",
                            name = wasm_name,
                        )
                        .into(),
                    ));
                }
                (Some(_), None) => {
                    layer.status.push(WasmDiffStatus::Bad(
                        format!(
                            "Wasm node lacked field present in elisp node. Name=({name}).",
                            name = wasm_name,
                        )
                        .into(),
                    ));
                }
                (Some(e), Some(serde_json::Value::Number(w)))
                    if w.as_u64().map(|w| w as usize) == Some(e) => {}
                (Some(e), Some(w)) => {
                    layer.status.push(WasmDiffStatus::Bad(
                        format!(
                            "Property value mismatch. Emacs=({emacs:?}) Wasm=({wasm:?}).",
                            emacs = e,
                            wasm = w,
                        )
                        .into(),
                    ));
                }
            }
        }
        result.children.push(layer);
    }

    {
        // Compare children.
        let mut layer = WasmDiffResult::<'_> {
            name: "children".into(),
            ..Default::default()
        };
        if let Some(wasm_iter) = wasm
            .get("children")
            .and_then(|children| children.as_array())
            .map(|children| children.iter())
        {
            layer.extend(wasm_compare_list(source, emacs_list_iter, wasm_iter)?)?;
        } else {
            layer.extend(wasm_compare_list(
                source,
                emacs_list_iter,
                std::iter::empty::<&serde_json::Value>(),
            )?)?;
        }
        result.children.push(layer);
    }

    Ok(result)
}

fn wasm_key_to_emacs_key<WK: std::fmt::Display>(wasm_key: WK) -> String {
    format!(":{key}", key = wasm_key)
}

fn compare_quoted_string<'s>(
    _source: &'s str,
    emacs: &str,
    wasm: &String,
) -> Result<WasmDiffResult<'s>, Box<dyn std::error::Error>> {
    let mut result = WasmDiffResult::default();
    let emacs_text = unquote(emacs)?;
    if wasm.as_str() != emacs_text {
        result.status.push(WasmDiffStatus::Bad(
            format!(
                "Text mismatch. Emacs=({emacs:?}) Wasm=({wasm:?}).",
                emacs = emacs_text,
                wasm = wasm,
            )
            .into(),
        ));
    }
    Ok(result)
}

pub(crate) fn wasm_get_emacs_standard_properties(
    attributes_map: &HashMap<&str, &Token<'_>>,
) -> Result<EmacsStandardProperties, Box<dyn std::error::Error>> {
    let standard_properties = attributes_map.get(":standard-properties");
    Ok(if standard_properties.is_some() {
        let mut std_props = standard_properties
            .expect("if statement proves its Some")
            .as_vector()?
            .iter();
        let begin = maybe_token_to_usize(std_props.next())?;
        let post_affiliated = maybe_token_to_usize(std_props.next())?;
        let contents_begin = maybe_token_to_usize(std_props.next())?;
        let contents_end = maybe_token_to_usize(std_props.next())?;
        let end = maybe_token_to_usize(std_props.next())?;
        let post_blank = maybe_token_to_usize(std_props.next())?;
        EmacsStandardProperties {
            begin,
            post_affiliated,
            contents_begin,
            contents_end,
            end,
            post_blank,
        }
    } else {
        let begin = maybe_token_to_usize(attributes_map.get(":begin").copied())?;
        let end = maybe_token_to_usize(attributes_map.get(":end").copied())?;
        let contents_begin = maybe_token_to_usize(attributes_map.get(":contents-begin").copied())?;
        let contents_end = maybe_token_to_usize(attributes_map.get(":contents-end").copied())?;
        let post_blank = maybe_token_to_usize(attributes_map.get(":post-blank").copied())?;
        let post_affiliated =
            maybe_token_to_usize(attributes_map.get(":post-affiliated").copied())?;
        EmacsStandardProperties {
            begin,
            post_affiliated,
            contents_begin,
            contents_end,
            end,
            post_blank,
        }
    })
}

fn wasm_compare_list<'e, 's: 'e, 'w, EI, WI>(
    source: &'s str,
    mut emacs: EI,
    wasm: WI,
) -> Result<WasmDiffResult<'s>, Box<dyn std::error::Error>>
where
    EI: Iterator<Item = &'e Token<'s>> + ExactSizeIterator,
    WI: Iterator<Item = &'w serde_json::Value> + ExactSizeIterator,
{
    let emacs_length = emacs.len();
    let wasm_length = wasm.len();
    if emacs_length == 1 && wasm_length == 0 && emacs.all(|t| matches!(t.as_atom(), Ok(r#""""#))) {
        return Ok(WasmDiffResult::default());
    }
    if emacs_length != wasm_length {
        return Ok(WasmDiffResult {
            status: vec![WasmDiffStatus::Bad(
                format!(
                    "Child length mismatch. Emacs=({emacs:?}) Wasm=({wasm:?}).",
                    emacs = emacs_length,
                    wasm = wasm_length
                )
                .into(),
            )],
            children: Vec::new(),
            name: "".into(),
        });
    }

    let mut child_status = Vec::with_capacity(emacs_length);
    for (emacs_child, wasm_child) in emacs.zip(wasm) {
        child_status.push(compare_json_value(source, emacs_child, wasm_child)?);
    }
    Ok(WasmDiffResult {
        status: Vec::new(),
        children: child_status,
        name: "".into(),
    })
}

fn compare_optional_pair<'s>(
    source: &'s str,
    emacs: &Vec<Token<'s>>,
    wasm: &serde_json::Map<String, serde_json::Value>,
) -> Result<WasmDiffResult<'s>, Box<dyn std::error::Error>> {
    let mut result = WasmDiffResult::default();
    let wasm_optval = wasm
        .get("optval")
        .ok_or(r#"Wasm optional pair should have an "optval" attribute."#)?;
    let wasm_val = wasm
        .get("val")
        .ok_or(r#"Wasm optional pair should have an "optval" attribute."#)?;
    if let serde_json::Value::Null = wasm_optval {
        // If the optval is null, then the elisp should have just a single value of a quoted string.
        if emacs.len() != 1 {
            return Ok(WasmDiffResult {
                status: vec![WasmDiffStatus::Bad(
                    format!(
                        "Optional pair with null optval should have 1 element. Emacs=({emacs:?}) Wasm=({wasm:?}).",
                        emacs = emacs,
                        wasm = wasm
                    )
                    .into(),
                )],
                children: Vec::new(),
                name: "".into(),
            });
        }

        let emacs_val = emacs
            .first()
            .expect("If-statement proves this will be Some.");
        result.extend(compare_json_value(source, emacs_val, wasm_val)?)?;
    } else {
        // If the optval is not null, then the elisp should have 3 values, the optval, a dot, and the val.
        if emacs.len() != 3 {
            return Ok(WasmDiffResult {
                status: vec![WasmDiffStatus::Bad(
                    format!(
                        "Optional pair with non-null optval should have 3 elements. Emacs=({emacs:?}) Wasm=({wasm:?}).",
                        emacs = emacs,
                        wasm = wasm
                    )
                    .into(),
                )],
                children: Vec::new(),
                name: "".into(),
            });
        }
        let emacs_optval = emacs
            .get(2)
            .expect("If-statement proves this will be Some.");
        let emacs_val = emacs
            .first()
            .expect("If-statement proves this will be Some.");
        result.extend(compare_json_value(source, emacs_optval, wasm_optval)?)?;
        result.extend(compare_json_value(source, emacs_val, wasm_val)?)?;
    }
    Ok(result)
}

fn compare_object_tree<'s>(
    source: &'s str,
    emacs: &[Token<'s>],
    wasm: &serde_json::Map<String, serde_json::Value>,
) -> Result<WasmDiffResult<'s>, Box<dyn std::error::Error>> {
    let mut result = WasmDiffResult::default();
    let wasm_attributes = wasm
        .get("object-tree")
        .ok_or(r#"Wasm object tree should have an "object-tree" attribute."#)?
        .as_array()
        .ok_or(r#"Wasm "object-tree" attribute should be a list."#)?;
    let emacs_outer_length = emacs.len();
    let wasm_outer_length = wasm_attributes.len();
    if emacs_outer_length != wasm_outer_length {
        result.status.push(WasmDiffStatus::Bad(
            format!(
                "Child length mismatch. Emacs=({emacs:?}) Wasm=({wasm:?}).",
                emacs = emacs_outer_length,
                wasm = wasm_outer_length
            )
            .into(),
        ));
        return Ok(result);
    }

    for (emacs_attribute, wasm_attribute) in emacs.iter().zip(wasm_attributes.iter()) {
        let wasm_attribute = wasm_attribute
            .as_array()
            .ok_or("Wasm middle layer in object tree should be a list.")?;
        if wasm_attribute.len() != 2 {
            result.status.push(WasmDiffStatus::Bad(
                format!(
                    "Wasm middle layer in object tree should have a length of 2. Wasm=({wasm:?}).",
                    wasm = wasm_attribute.len()
                )
                .into(),
            ));
            return Ok(result);
        }
        if let Ok("nil") = emacs_attribute.as_atom() {
            if let Some(serde_json::Value::Null) = wasm_attribute.first() {
                if let Some(serde_json::Value::Array(w)) = wasm_attribute.get(1) {
                    if w.is_empty() {
                        continue;
                    }
                }
            }
        }
        let emacs_attribute = emacs_attribute.as_list()?;
        if let Some(serde_json::Value::Null) = wasm_attribute.first() {
            // If optval is null then the emacs array should only contain 1 value.
            if emacs_attribute.len() != 1 {
                result.status.push(WasmDiffStatus::Bad(
                    format!(
                        "Emacs middle layer in object tree should have a length of 1. Emacs=({emacs:?}) Wasm=({wasm:?}).",
                        emacs = emacs_attribute,
                    wasm = wasm_attribute
                )
                    .into(),
                ));
                return Ok(result);
            }

            let emacs_val = emacs_attribute
                .first()
                .expect("If-statement proves this will be Some.");
            let wasm_val = wasm_attribute
                .get(1)
                .expect("If-statement proves this will be Some.");
            result.extend(compare_json_value(source, emacs_val, wasm_val)?)?;
        } else {
            // If optval is not null, then the emacs array should contain a list, the first child of which is a list for optval, and all other entries to the outer list are the val.
            if emacs_attribute.len() < 2 {
                result.status.push(WasmDiffStatus::Bad(
                    format!(
                        "Emacs middle layer in object tree should have a length of at least 2. Emacs=({emacs:?}) Wasm=({wasm:?}).",
                        emacs = emacs_attribute,
                    wasm = wasm_attribute
                )
                    .into(),
                ));
                return Ok(result);
            }
            let emacs_optval = emacs_attribute.iter().skip(1);
            let wasm_optval = wasm_attribute
                .first()
                .expect("If-statement proves this will be Some.")
                .as_array()
                .ok_or("first value in wasm object tree should be a list.")?;
            let emacs_val = emacs_attribute
                .first()
                .ok_or("If-statement proves this will be Some.")?;
            let wasm_val = wasm_attribute
                .get(1)
                .expect("If-statement proves this will be Some.")
                .as_array()
                .ok_or("2nd value in wasm object tree should be a list.")?;
            result.extend(wasm_compare_list(source, emacs_optval, wasm_optval.iter())?)?;
            if let Ok("nil") = emacs_val.as_atom() {
                result.extend(wasm_compare_list(
                    source,
                    std::iter::empty(),
                    wasm_val.iter(),
                )?)?;
            } else {
                result.extend(wasm_compare_list(
                    source,
                    emacs_val.as_list()?.iter(),
                    wasm_val.iter(),
                )?)?;
            }
        }
    }

    Ok(result)
}

fn compare_number_lines<'s>(
    _source: &'s str,
    emacs: &[Token<'s>],
    wasm: &serde_json::Map<String, serde_json::Value>,
) -> Result<WasmDiffResult<'s>, Box<dyn std::error::Error>> {
    let mut result = WasmDiffResult::default();
    let mut emacs_iter = emacs.iter();
    let emacs_directive = emacs_iter
        .next()
        .ok_or("Emacs number lines should have 3 children.")?
        .as_atom()?;
    let emacs_number: i64 = emacs_iter
        .nth(1)
        .ok_or("Emacs number lines should have 3 children.")?
        .as_atom()?
        .parse()?;
    if wasm.contains_key("new") {
        let wasm_number = wasm
            .get("new")
            .ok_or(r#"Wasm number lines should have a "new" attribute."#)?
            .as_i64()
            .ok_or(r#"Wasm number lines "new" attribute should be a number."#)?;
        if emacs_directive != "new" {
            result.status.push(WasmDiffStatus::Bad(
                format!(
                    "Number lines directive mismatch. Emacs=({emacs:?}) Wasm=({wasm:?}).",
                    emacs = emacs_directive,
                    wasm = "new"
                )
                .into(),
            ));
            return Ok(result);
        }
        if emacs_number != wasm_number {
            result.status.push(WasmDiffStatus::Bad(
                format!(
                    "Number lines number mismatch. Emacs=({emacs:?}) Wasm=({wasm:?}).",
                    emacs = emacs_number,
                    wasm = wasm_number
                )
                .into(),
            ));
            return Ok(result);
        }
    } else if wasm.contains_key("continued") {
        let wasm_number = wasm
            .get("continued")
            .ok_or(r#"Wasm number lines should have a "continued" attribute."#)?
            .as_i64()
            .ok_or(r#"Wasm number lines "continued" attribute should be a number."#)?;
        if emacs_directive != "continued" {
            result.status.push(WasmDiffStatus::Bad(
                format!(
                    "Number lines directive mismatch. Emacs=({emacs:?}) Wasm=({wasm:?}).",
                    emacs = emacs_directive,
                    wasm = "continued"
                )
                .into(),
            ));
            return Ok(result);
        }
        if emacs_number != wasm_number {
            result.status.push(WasmDiffStatus::Bad(
                format!(
                    "Number lines number mismatch. Emacs=({emacs:?}) Wasm=({wasm:?}).",
                    emacs = emacs_number,
                    wasm = wasm_number
                )
                .into(),
            ));
            return Ok(result);
        }
    } else {
        result.status.push(WasmDiffStatus::Bad(
            format!(
                "Unrecognized number lines directive. Wasm=({wasm:?}).",
                wasm = wasm
            )
            .into(),
        ));
        return Ok(result);
    }

    Ok(result)
}

fn compare_string_set<'s>(
    _source: &'s str,
    emacs: &[Token<'s>],
    wasm: &serde_json::Map<String, serde_json::Value>,
) -> Result<WasmDiffResult<'s>, Box<dyn std::error::Error>> {
    let mut result = WasmDiffResult::default();
    let wasm_list = wasm
        .get("value")
        .ok_or(r#"Wasm string set should have a "value" attribute."#)?
        .as_array()
        .ok_or(r#"Wasm string set "value" attribute should be a list."#)?;
    let wasm_strings = wasm_list
        .iter()
        .map(|v| v.as_str().ok_or("Non-string in wasm string set."))
        .collect::<Result<BTreeSet<_>, &'static str>>()?;
    let emacs_strings = emacs
        .iter()
        .map(|v| v.as_atom())
        .collect::<Result<Vec<_>, Box<dyn std::error::Error>>>()?
        .into_iter()
        .map(unquote)
        .collect::<Result<Vec<_>, Box<dyn std::error::Error>>>()?;
    let emacs_strings = emacs_strings
        .iter()
        .map(|s| s.borrow())
        .collect::<BTreeSet<&str>>();

    let mismatched: Vec<_> = emacs_strings
        .symmetric_difference(&wasm_strings)
        .copied()
        .collect();
    if !mismatched.is_empty() {
        result.status.push(WasmDiffStatus::Bad(
            format!(
                "String set mismatch. MismatchedValues=({values:?}).",
                values = mismatched.join(", ")
            )
            .into(),
        ));
    }

    Ok(result)
}

fn is_plain_text(wasm: &serde_json::Map<String, serde_json::Value>) -> bool {
    if let Some(serde_json::Value::String(node_type)) = wasm.get("ast-node") {
        node_type == "plain-text"
    } else {
        false
    }
}

fn compare_plain_text<'s>(
    source: &'s str,
    emacs: &TextWithProperties<'s>,
    wasm: &serde_json::Map<String, serde_json::Value>,
) -> Result<WasmDiffResult<'s>, Box<dyn std::error::Error>> {
    let mut result = WasmDiffResult::<'_> {
        name: "plain-text".into(),
        ..Default::default()
    };
    if !is_plain_text(wasm) {
        result.status.push(WasmDiffStatus::Bad(
            format!(
                "AST node type mismatch. Emacs=({emacs:?}) Wasm=({wasm:?}).",
                emacs = emacs,
                wasm = wasm,
            )
            .into(),
        ));
        return Ok(result);
    }

    let emacs_text = unquote(emacs.text)?;
    let wasm_standard_properties = wasm
        .get("standard-properties")
        .ok_or(r#"Wasm AST nodes should have a "standard-properties" attribute."#)?
        .as_object()
        .ok_or(r#"Wasm ast node "standard-properties" attribute should be an object."#)?;
    let wasm_begin = {
        if let Some(serde_json::Value::Number(begin)) = wasm_standard_properties.get("begin") {
            begin
                .as_u64()
                .map(|w| w as usize)
                .ok_or("Begin should be a number.")?
        } else {
            result.status.push(WasmDiffStatus::Bad(
                format!(
                    "AST node type mismatch. Emacs=({emacs:?}) Wasm=({wasm:?}).",
                    emacs = emacs,
                    wasm = wasm,
                )
                .into(),
            ));
            return Ok(result);
        }
    };
    let wasm_end = {
        if let Some(serde_json::Value::Number(end)) = wasm_standard_properties.get("end") {
            end.as_u64()
                .map(|w| w as usize)
                .ok_or("End should be a number.")?
        } else {
            result.status.push(WasmDiffStatus::Bad(
                format!(
                    "AST node type mismatch. Emacs=({emacs:?}) Wasm=({wasm:?}).",
                    emacs = emacs,
                    wasm = wasm,
                )
                .into(),
            ));
            return Ok(result);
        }
    };
    let wasm_text: String = source
        .chars()
        .skip(wasm_begin - 1)
        .take(wasm_end - wasm_begin)
        .collect();
    if wasm_text != emacs_text {
        result.status.push(WasmDiffStatus::Bad(
            format!(
                "Text mismatch. Emacs=({emacs:?}) Wasm=({wasm:?}).",
                emacs = emacs_text,
                wasm = wasm_text,
            )
            .into(),
        ));
        return Ok(result);
    }

    let emacs_start = emacs
        .properties
        .first()
        .map(|t| t.as_atom())
        .map_or(Ok(None), |r| r.map(Some))?;
    if emacs_start != Some("0") {
        result.status.push(WasmDiffStatus::Bad(
            format!(
                "Text should start at offset 0. Emacs=({emacs:?}) Wasm=({wasm:?}).",
                emacs = emacs,
                wasm = wasm,
            )
            .into(),
        ));
    }
    let emacs_end = emacs
        .properties
        .get(1)
        .map(|t| t.as_atom())
        .map_or(Ok(None), |r| r.map(Some))?;
    if emacs_end != Some((wasm_end - wasm_begin).to_string().as_str()) {
        result.status.push(WasmDiffStatus::Bad(
            format!(
                "Text end mismatch. Emacs=({emacs:?}) Wasm=({wasm:?}).",
                emacs = emacs_end,
                wasm = wasm_end - wasm_begin,
            )
            .into(),
        ));
    }

    Ok(result)
}