duster/src/bin.rs

extern crate nom;

use crate::renderer::CompareContextElement;
use parser::Filter;
use parser::OwnedLiteral;
use renderer::compile_template;
use renderer::CompiledTemplate;
use renderer::ContextElement;
use renderer::DustRenderer;
use renderer::Loopable;
use renderer::RenderError;
use renderer::Renderable;
use renderer::WalkError;
use renderer::Walkable;
use std::cmp::Ordering;
use std::env;
use std::fs;
use std::io::{self, Read};
use std::path::Path;

mod parser;
mod renderer;

fn main() {
    let context = read_context_from_stdin();

    let argv: Vec<String> = env::args().collect();
    if argv.len() < 2 {
        panic!("Need to pass templates");
    }
    let template_paths = &argv[1..];
    let template_contents: Vec<(String, String)> = template_paths
        .iter()
        .map(|p| {
            let template_content = fs::read_to_string(&p).unwrap();
            (p.to_string(), template_content)
        })
        .collect();
    let compiled_templates: Vec<CompiledTemplate> = template_contents
        .iter()
        .map(|(p, contents)| template_from_file(p, contents))
        .collect();
    let mut dust_renderer = DustRenderer::new();
    compiled_templates.iter().for_each(|template| {
        dust_renderer.load_source(template);
    });
    let main_template_name = &compiled_templates
        .first()
        .expect("There should be more than 1 template")
        .name;
    let breadcrumbs = vec![&context as &dyn ContextElement];
    println!(
        "{}",
        dust_renderer
            .render(main_template_name, &breadcrumbs)
            .expect("Failed to render")
    );
}

fn template_from_file<'a>(file_path: &str, file_contents: &'a str) -> CompiledTemplate<'a> {
    let path: &Path = Path::new(file_path);
    let name = path.file_stem().unwrap();
    compile_template(file_contents, name.to_string_lossy().to_string())
        .expect("Failed to compile template")
}

fn read_context_from_stdin() -> serde_json::Value {
    let mut buffer = String::new();
    io::stdin()
        .read_to_string(&mut buffer)
        .expect("Failed to read stdin");

    serde_json::from_str(&buffer).expect("Failed to parse json")
}

fn html_escape(inp: &str) -> String {
    // Adding 10% space from the original to avoid re-allocations by
    // leaving room for escaped sequences.
    let mut output = String::with_capacity(((inp.len() as f64) * 1.1) as usize);
    inp.chars().for_each(|c| match c {
        '<' => output.push_str("&lt;"),
        '>' => output.push_str("&gt;"),
        '"' => output.push_str("&quot;"),
        '\'' => output.push_str("&#39;"),
        '&' => output.push_str("&amp;"),
        _ => output.push(c),
    });
    output
}

fn javascript_escape(inp: &str) -> String {
    // Adding 10% space from the original to avoid re-allocations by
    // leaving room for escaped sequences.
    let mut output = String::with_capacity(((inp.len() as f64) * 1.1) as usize);
    inp.chars().for_each(|c| match c {
        '"' => output.push_str(r#"\""#),
        '\'' => output.push_str(r#"\'"#),
        '\t' => output.push_str(r#"\t"#),
        '\x0C' => output.push_str(r#"\f"#),
        '\n' => output.push_str(r#"\n"#),
        '\r' => output.push_str(r#"\r"#),
        '\\' => output.push_str(r#"\\"#),
        '/' => output.push_str(r#"\/"#),
        _ => output.push(c),
    });
    output
}

fn get_utf8_hex(inp: char) -> String {
    let num_bytes = inp.len_utf8();
    let mut byte_buffer = [0; 4]; // UTF-8 supports up to 4 bytes per codepoint
    let mut output = String::with_capacity(num_bytes * 2);

    inp.encode_utf8(&mut byte_buffer);

    for b in &byte_buffer[..num_bytes] {
        output.push_str(&format!("{:02X}", b));
    }

    output
}

fn encode_uri(inp: &str) -> String {
    // Adding 10% space from the original to avoid re-allocations by
    // leaving room for escaped sequences.
    let mut output = String::with_capacity(((inp.len() as f64) * 1.1) as usize);
    inp.chars().for_each(|c| match c {
        '0' | '1' | '2' | '3' | '4' | '5' | '6' | '7' | '8' | '9' | 'a' | 'b' | 'c' | 'd' | 'e'
        | 'f' | 'g' | 'h' | 'i' | 'j' | 'k' | 'l' | 'm' | 'n' | 'o' | 'p' | 'q' | 'r' | 's'
        | 't' | 'u' | 'v' | 'w' | 'x' | 'y' | 'z' | 'A' | 'B' | 'C' | 'D' | 'E' | 'F' | 'G'
        | 'H' | 'I' | 'J' | 'K' | 'L' | 'M' | 'N' | 'O' | 'P' | 'Q' | 'R' | 'S' | 'T' | 'U'
        | 'V' | 'W' | 'X' | 'Y' | 'Z' | ';' | ',' | '/' | '?' | ':' | '@' | '&' | '=' | '+'
        | '$' | '-' | '_' | '.' | '!' | '~' | '*' | '\'' | '(' | ')' | '#' => output.push(c),
        _ => {
            output.push('%');
            output.push_str(&get_utf8_hex(c));
        }
    });
    output
}

fn encode_uri_component(inp: &str) -> String {
    // Adding 10% space from the original to avoid re-allocations by
    // leaving room for escaped sequences.
    let mut output = String::with_capacity(((inp.len() as f64) * 1.1) as usize);
    inp.chars().for_each(|c| match c {
        '0' | '1' | '2' | '3' | '4' | '5' | '6' | '7' | '8' | '9' | 'a' | 'b' | 'c' | 'd' | 'e'
        | 'f' | 'g' | 'h' | 'i' | 'j' | 'k' | 'l' | 'm' | 'n' | 'o' | 'p' | 'q' | 'r' | 's'
        | 't' | 'u' | 'v' | 'w' | 'x' | 'y' | 'z' | 'A' | 'B' | 'C' | 'D' | 'E' | 'F' | 'G'
        | 'H' | 'I' | 'J' | 'K' | 'L' | 'M' | 'N' | 'O' | 'P' | 'Q' | 'R' | 'S' | 'T' | 'U'
        | 'V' | 'W' | 'X' | 'Y' | 'Z' | '-' | '_' | '.' | '!' | '~' | '*' | '\'' | '(' | ')' => {
            output.push(c)
        }
        _ => {
            output.push('%');
            output.push_str(&get_utf8_hex(c));
        }
    });
    output
}

fn apply_filter(
    json_value: &serde_json::Value,
    filter: &Filter,
) -> Result<serde_json::Value, RenderError> {
    match (json_value, filter) {
        // Html escape filter
        (serde_json::Value::String(string), Filter::HtmlEncode) => {
            Ok(serde_json::Value::String(html_escape(string)))
        }
        (_, Filter::HtmlEncode) => Ok(serde_json::Value::String(html_escape(
            &json_value.render(&Vec::new())?,
        ))),
        // Disable html escape filter
        (_, Filter::DisableHtmlEncode) => panic!("The |s filter is automatically removed by the renderer since it is a no-op during rendering."),
        // Parse JSON filter
        (serde_json::Value::String(string), Filter::JsonParse) => {
            serde_json::from_str(&string).or(Err(RenderError::InvalidJson(string.to_owned())))
        }
        (_, Filter::JsonParse) => {
            let rendered_value = json_value.render(&Vec::new())?;
            serde_json::from_str(&rendered_value).or(Err(RenderError::InvalidJson(rendered_value)))
        }
        // Json Stringify filter
        (_, Filter::JsonStringify) => {
            Ok(serde_json::Value::String(json_value.to_string()))
        }
        // Javascript escape filter
        (serde_json::Value::String(string), Filter::JavascriptStringEncode) => {
            Ok(serde_json::Value::String(javascript_escape(string)))
        }
        (serde_json::Value::Bool(boolean), Filter::JavascriptStringEncode) => {
            Ok(serde_json::Value::Bool(*boolean))
        }
        (serde_json::Value::Number(number), Filter::JavascriptStringEncode) => {
            Ok(serde_json::Value::Number(number.clone()))
        }
        (_, Filter::JavascriptStringEncode) => Ok(serde_json::Value::String(javascript_escape(
            &json_value.render(&Vec::new())?,
        ))),
        // EncodeURI filter
        (serde_json::Value::String(string), Filter::EncodeUri) => {
            Ok(serde_json::Value::String(encode_uri(string)))
        }
        (_, Filter::EncodeUri) => Ok(serde_json::Value::String(encode_uri(
            &json_value.render(&Vec::new())?,
        ))),
        // EncodeURIComponent filter
        (serde_json::Value::String(string), Filter::EncodeUriComponent) => {
            Ok(serde_json::Value::String(encode_uri_component(string)))
        }
        (_, Filter::EncodeUriComponent) => Ok(serde_json::Value::String(encode_uri_component(
            &json_value.render(&Vec::new())?,
        ))),
    }
}

fn apply_filters(
    json_value: &serde_json::Value,
    filters: &[Filter],
) -> Result<serde_json::Value, RenderError> {
    let mut final_value: serde_json::Value = apply_filter(json_value, &filters[0])?;

    for filter in &filters[1..] {
        final_value = apply_filter(&final_value, filter)?;
    }

    Ok(final_value)
}

impl ContextElement for serde_json::Value {}

impl Renderable for serde_json::Value {
    fn render(&self, _filters: &Vec<Filter>) -> Result<String, RenderError> {
        let after_apply = if _filters.is_empty() {
            None
        } else {
            Some(apply_filters(self, _filters)?)
        };

        match after_apply.as_ref().unwrap_or(self) {
            serde_json::Value::Null => Ok("".to_owned()),
            serde_json::Value::Bool(boolean) => Ok(boolean.to_string()),
            serde_json::Value::Number(num) => Ok(num.to_string()),
            serde_json::Value::String(string) => Ok(string.to_string()),
            serde_json::Value::Array(arr) => {
                // TODO: Handle the filters instead of passing a Vec::new()
                let rendered: Result<Vec<String>, RenderError> =
                    arr.iter().map(|val| val.render(&Vec::new())).collect();
                let rendered_slice: &[String] = &rendered?;
                Ok(rendered_slice.join(","))
            }
            serde_json::Value::Object(_obj) => Ok("[object Object]".to_owned()),
        }
    }
}

impl Walkable for serde_json::Value {
    fn walk(&self, segment: &str) -> Result<&dyn ContextElement, WalkError> {
        match self {
            serde_json::Value::Null => Err(WalkError::CantWalk),
            serde_json::Value::Bool(_boolean) => Err(WalkError::CantWalk),
            serde_json::Value::Number(_num) => Err(WalkError::CantWalk),
            serde_json::Value::String(_string) => Err(WalkError::CantWalk),
            serde_json::Value::Array(_arr) => Err(WalkError::CantWalk),
            serde_json::Value::Object(obj) => obj
                .get(segment)
                .map(|val| val as _)
                .ok_or(WalkError::CantWalk),
        }
    }
}

impl Loopable for serde_json::Value {
    fn get_loop_elements(&self) -> Vec<&dyn ContextElement> {
        match self {
            serde_json::Value::Null => Vec::new(),
            serde_json::Value::Bool(boolean) => {
                if *boolean {
                    vec![self]
                } else {
                    Vec::new()
                }
            }
            serde_json::Value::Number(_num) => vec![self],
            serde_json::Value::String(string_value) => {
                if string_value.is_empty() {
                    Vec::new()
                } else {
                    vec![self]
                }
            }
            serde_json::Value::Array(array_value) => {
                if array_value.is_empty() {
                    Vec::new()
                } else {
                    array_value.iter().map(|x| x as _).collect()
                }
            }
            serde_json::Value::Object(_obj) => vec![self],
        }
    }
}

impl CompareContextElement for serde_json::Value {
    fn equals(&self, other: &dyn ContextElement) -> bool {
        // println!("equals json {:?} | {:?}", self, other);
        // Handle other serde_json::Value
        match other.to_any().downcast_ref::<Self>() {
            None => (),
            Some(other_json_value) => match (self, other_json_value) {
                // Non-scalar values not caught in the renderer by the
                // identical-path shortcut are always not equal.
                (serde_json::Value::Array(_), _)
                | (_, serde_json::Value::Array(_))
                | (serde_json::Value::Object(_), _)
                | (_, serde_json::Value::Object(_)) => return false,
                _ => return self == other_json_value,
            },
        }
        // Handle literals
        match other.to_any().downcast_ref::<OwnedLiteral>() {
            None => (),
            Some(OwnedLiteral::LString(other_string)) => {
                return self.as_str().map_or(false, |s| s == other_string)
            }
            Some(OwnedLiteral::LPositiveInteger(other_num)) => {
                return self.as_u64().map_or(false, |n| n == *other_num)
            }
        }
        false
    }

    fn partial_compare(&self, other: &dyn ContextElement) -> Option<Ordering> {
        // println!("partial_compare json {:?} | {:?}", self, other);
        // Handle type coerced objects

        // When doing a greater than or less than comparison,
        // javascript coerces objects into "[object Object]".
        if let serde_json::Value::Object(_) = self {
            return OwnedLiteral::LString(self.render(&Vec::new()).unwrap_or("".to_owned()))
                .partial_compare(other);
        }

        // When doing a greater than or less than comparison
        // javascript turns arrays into strings.
        if let serde_json::Value::Array(_) = self {
            return OwnedLiteral::LString(self.render(&Vec::new()).unwrap_or("".to_owned()))
                .partial_compare(other);
        }

        // Handle other serde_json::Value
        match other.to_any().downcast_ref::<Self>() {
            None => (),
            Some(other_json_value) => {
                return match (self, other_json_value) {
                    (
                        serde_json::Value::Bool(self_boolean),
                        serde_json::Value::Bool(other_boolean),
                    ) => self_boolean.partial_cmp(other_boolean),
                    (
                        serde_json::Value::Number(self_number),
                        serde_json::Value::Number(other_number),
                    ) => return compare_json_numbers(self_number, other_number),
                    (
                        serde_json::Value::String(self_string),
                        serde_json::Value::Number(other_number),
                    ) => return compare_json_numbers(self_string, other_number),
                    (
                        serde_json::Value::Number(self_number),
                        serde_json::Value::String(other_string),
                    ) => return compare_json_numbers(self_number, other_string),
                    (
                        serde_json::Value::String(self_string),
                        serde_json::Value::String(other_string),
                    ) => self_string.partial_cmp(other_string),
                    (
                        serde_json::Value::Array(self_array),
                        serde_json::Value::Array(other_array),
                    ) => {
                        return self
                            .render(&Vec::new())
                            .unwrap_or("".to_owned())
                            .partial_cmp(
                                &other_json_value
                                    .render(&Vec::new())
                                    .unwrap_or("".to_owned()),
                            )
                    }
                    _ => None,
                };
            }
        }
        // Handle literals
        match other.to_any().downcast_ref::<OwnedLiteral>() {
            None => (),
            Some(other_literal) => match (self, other_literal) {
                (serde_json::Value::String(self_string), OwnedLiteral::LString(other_string)) => {
                    return self_string.partial_cmp(other_string)
                }
                (
                    serde_json::Value::String(self_string),
                    OwnedLiteral::LPositiveInteger(other_num),
                ) => return compare_json_numbers(self_string, other_literal),
                (serde_json::Value::Number(self_num), OwnedLiteral::LString(other_string)) => {
                    return compare_json_numbers(self_num, other_string)
                }
                (
                    serde_json::Value::Number(self_num),
                    OwnedLiteral::LPositiveInteger(other_num),
                ) => return compare_json_numbers(self_num, other_literal),
                (serde_json::Value::Array(_), _) => {
                    // TODO
                    todo!()
                }
                (serde_json::Value::Object(_), _) => {
                    // TODO
                    todo!()
                }
                (serde_json::Value::Bool(_), _) => {
                    // TODO
                    todo!()
                }
                (serde_json::Value::Null, _) => {
                    // TODO
                    todo!()
                }
            },
        }
        None
    }
}

/// Create a new vec by of references to the serde_json::Values as
/// ContextElement trait objects so we can use its implementation of
/// PartialOrd.
///
/// You cannot implement a trait you do not define for a type you do
/// not define, so I cannot implement PartialOrd for
/// serde_json::value. Instead, I just re-use the PartialOrd
/// implementation for ContextElement which unfortunately has extra
/// overhead of downcasting. This would be a good spot for
/// optimization.
fn convert_vec_to_context_element(array: &Vec<serde_json::Value>) -> Vec<&dyn ContextElement> {
    array.iter().map(|v| v as _).collect()
}

#[derive(Debug)]
enum JsonNumber {
    UnsignedInteger(u64),
    SignedInteger(i64),
    Decimal(f64),
    Failure,
}

impl From<&String> for JsonNumber {
    fn from(original: &String) -> Self {
        match original.parse::<u64>() {
            Ok(num) => return JsonNumber::UnsignedInteger(num),
            Err(_) => (),
        };
        match original.parse::<i64>() {
            Ok(num) => return JsonNumber::SignedInteger(num),
            Err(_) => (),
        };
        match original.parse::<f64>() {
            Ok(num) => return JsonNumber::Decimal(num),
            Err(_) => (),
        };
        JsonNumber::Failure
    }
}

impl From<&serde_json::Number> for JsonNumber {
    fn from(original: &serde_json::Number) -> Self {
        match original.as_u64() {
            Some(num) => return JsonNumber::UnsignedInteger(num),
            None => (),
        };
        match original.as_i64() {
            Some(num) => return JsonNumber::SignedInteger(num),
            None => (),
        };
        match original.as_f64() {
            Some(num) => return JsonNumber::Decimal(num),
            None => (),
        };
        JsonNumber::Failure
    }
}

impl From<&OwnedLiteral> for JsonNumber {
    fn from(original: &OwnedLiteral) -> Self {
        match original {
            OwnedLiteral::LPositiveInteger(num) => JsonNumber::UnsignedInteger(*num),
            OwnedLiteral::LString(text) => text.into(),
        }
    }
}

/// Compare json numbers
///
/// While this function can be called with two strings, it would not
/// make sense because javascript does not use numeric comparisons for
/// strings
fn compare_json_numbers<S, O>(self_input: S, other_input: O) -> Option<Ordering>
where
    S: Into<JsonNumber>,
    O: Into<JsonNumber>,
{
    let self_number: JsonNumber = self_input.into();
    let other_number: JsonNumber = other_input.into();
    // println!(
    //     "compare_number_and_string {:?} | {:?}",
    //     self_number, other_number
    // );
    // TODO: Figure out how javascript compares floats and ints
    match (self_number, other_number) {
        (JsonNumber::Failure, _) => return None,
        (_, JsonNumber::Failure) => return None,
        (JsonNumber::UnsignedInteger(self_num), JsonNumber::UnsignedInteger(other_num)) => {
            return self_num.partial_cmp(&other_num)
        }
        (JsonNumber::UnsignedInteger(self_num), JsonNumber::SignedInteger(other_num)) => {
            return Some(Ordering::Greater)
        }
        (JsonNumber::UnsignedInteger(self_num), JsonNumber::Decimal(other_num)) => return None,

        (JsonNumber::SignedInteger(self_num), JsonNumber::UnsignedInteger(other_num)) => {
            return Some(Ordering::Less)
        }
        (JsonNumber::SignedInteger(self_num), JsonNumber::SignedInteger(other_num)) => {
            return self_num.partial_cmp(&other_num)
        }
        (JsonNumber::SignedInteger(self_num), JsonNumber::Decimal(other_num)) => return None,

        (JsonNumber::Decimal(self_num), JsonNumber::UnsignedInteger(other_num)) => return None,
        (JsonNumber::Decimal(self_num), JsonNumber::SignedInteger(other_num)) => return None,
        (JsonNumber::Decimal(self_num), JsonNumber::Decimal(other_num)) => {
            return self_num.partial_cmp(&other_num)
        }
    }
    None
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_nested_array_render() {
        let x: serde_json::Value =
            serde_json::from_str(r#"[3,5,[7,9]]"#).expect("Failed to parse json");
        assert_eq!(
            x.render(&Vec::new()),
            Ok::<_, RenderError>("3,5,7,9".to_owned())
        );
    }

    #[test]
    fn test_html_escape() {
        assert_eq!(html_escape("<>&\"'"), "&lt;&gt;&amp;&quot;&#39;".to_owned())
    }
}