extern crate nom;

use renderer::compile_template;
use renderer::CompiledTemplate;
use renderer::ContextElement;
use renderer::DustRenderer;
use renderer::RenderError;
use renderer::Renderable;
use renderer::Walkable;
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;
    println!(
        "{}",
        dust_renderer
            .render(main_template_name, &context)
            .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");

    let parsed: serde_json::Value = serde_json::from_str(&buffer).expect("Failed to parse json");
    match parsed {
        serde_json::Value::Object(obj) => serde_json::value::Value::Object(obj),
        _ => panic!("Expected context to be an object"),
    }
}

impl ContextElement for serde_json::Value {}

impl Renderable for serde_json::Value {
    fn render(&self) -> String {
        match self {
            serde_json::Value::Null => "".to_owned(),
            serde_json::Value::Bool(boolean) => boolean.to_string(),
            serde_json::Value::Number(num) => num.to_string(),
            serde_json::Value::String(string) => string.to_string(),
            serde_json::Value::Array(_arr) => panic!("Attempted to render an array"),
            serde_json::Value::Object(_obj) => panic!("Attempted to render an object"),
        }
    }
}

impl Walkable for serde_json::Value {
    fn walk(&self, segment: &str) -> Result<&dyn ContextElement, RenderError> {
        match self {
            serde_json::Value::Null => Err(RenderError::CantWalk {
                segment: segment.to_string(),
                elem: self,
            }),
            serde_json::Value::Bool(_boolean) => Err(RenderError::CantWalk {
                segment: segment.to_string(),
                elem: self,
            }),
            serde_json::Value::Number(_num) => Err(RenderError::CantWalk {
                segment: segment.to_string(),
                elem: self,
            }),
            serde_json::Value::String(_string) => Err(RenderError::CantWalk {
                segment: segment.to_string(),
                elem: self,
            }),
            serde_json::Value::Array(_arr) => todo!("Arrays not supported yet"),
            // TODO: Handle this error better
            serde_json::Value::Object(obj) => {
                obj.get(segment)
                    .map(|val| val as _)
                    .ok_or(RenderError::WontWalk {
                        segment: segment.to_string(),
                        elem: self,
                    })
            }
        }
    }
}