use std::{collections::HashMap, ops::Range, rc::Rc, sync::Once};

use ariadne::{Fmt, Label, Report, ReportKind};
use crypto::{digest::Digest, sha2::Sha512};
use regex::{Captures, Regex};
use syntect::{easy::HighlightLines, highlighting::ThemeSet, parsing::SyntaxSet};

use crate::{cache::cache::{Cached, CachedError}, compiler::compiler::{Compiler, Target}, document::{document::Document, element::{ElemKind, Element}}, parser::{parser::Parser, rule::RegexRule, source::{Source, Token}, util::{self, Property, PropertyParser}}};
use lazy_static::lazy_static;

#[derive(Clone, Copy, Debug, PartialEq, Eq)]
enum CodeKind
{
	FullBlock,
	MiniBlock,
	Inline,
}

#[derive(Debug)]
struct Code
{
	location: Token,
	block: CodeKind,
	language: String,
	name: Option<String>,
	code: String,
	theme: Option<String>,
	line_offset: usize,
}

impl Code {
    fn new(location: Token, block: CodeKind, language: String, name: Option<String>, code: String, theme: Option<String>, line_offset: usize) -> Self {
        Self { location, block, language, name, code, theme, line_offset }
    }

	fn highlight_html(&self, compiler: &Compiler) -> Result<String, String>
	{
		lazy_static! {
			static ref syntax_set : SyntaxSet = SyntaxSet::load_defaults_newlines();
			static ref theme_set : ThemeSet = ThemeSet::load_defaults();
		}
		let syntax = match syntax_set.find_syntax_by_name(self.language.as_str())
		{
			Some(syntax) => syntax,
			None => return Err(format!("Unable to find syntax for language: {}", self.language))
		};

		let theme_string = match self.theme.as_ref()
		{
			Some(theme) => theme.as_str(),
			None => "base16-ocean.dark",
		};
		let mut h = HighlightLines::new(syntax, &theme_set.themes[theme_string]);

		let mut result = String::new();
		if self.block == CodeKind::FullBlock
		{
			result += "<div class=\"code-block\">";
			if let Some(name) = &self.name
			{
				result += format!("<div class=\"code-block-title\">{}</div>",
					compiler.sanitize(name.as_str())).as_str();
			}

			result += format!("<div class=\"code-block-content\"><table cellspacing=\"0\">").as_str();
			for (line_id, line) in self.code.split(|c| c == '\n').enumerate()
			{
				result += "<tr><td class=\"code-block-gutter\">";

				// Line number
				result += format!("<pre><span>{}</span></pre>", line_id+self.line_offset).as_str();

				// Code
				result += "</td><td class=\"code-block-line\"><pre>";
				match h.highlight_line(line, &syntax_set)
				{
					Err(e) => return Err(format!("Error highlighting line `{line}`: {}", e.to_string())),
					Ok(regions) => {
						match syntect::html::styled_line_to_highlighted_html(&regions[..], syntect::html::IncludeBackground::No)
						{
							Err(e) => return Err(format!("Error highlighting code: {}", e.to_string())),
							Ok(highlighted) => result += if highlighted.is_empty() { "<br>" } else { highlighted.as_str() }
						}
					}
				}
				result += "</pre></td></tr>";
			}

			result += "</table></div></div>";
		}
		else if self.block == CodeKind::MiniBlock
		{
			result += "<div class=\"code-block\"><div class=\"code-block-content\"><table cellspacing=\"0\">";

			for line in self.code.split(|c| c == '\n')
			{
				result += "<tr><td class=\"code-block-line\"><pre>";
				// Code
				match h.highlight_line(line, &syntax_set)
				{
					Err(e) => return Err(format!("Error highlighting line `{line}`: {}", e.to_string())),
					Ok(regions) => {
						match syntect::html::styled_line_to_highlighted_html(&regions[..], syntect::html::IncludeBackground::No)
						{
							Err(e) => return Err(format!("Error highlighting code: {}", e.to_string())),
							Ok(highlighted) => result += if highlighted.is_empty() { "<br>" } else { highlighted.as_str() }
						}
					}
				}
				result += "</pre></td></tr>";
			}
			result += "</table></div></div>";
		}
		else if self.block == CodeKind::Inline
		{
			result += "<a class=\"inline-code\"><code>";
			match h.highlight_line(self.code.as_str(), &syntax_set)
			{
				Err(e) => return Err(format!("Error highlighting line `{}`: {}", self.code, e.to_string())),
				Ok(regions) => {
					match syntect::html::styled_line_to_highlighted_html(&regions[..], syntect::html::IncludeBackground::No)
					{
						Err(e) => return Err(format!("Error highlighting code: {}", e.to_string())),
						Ok(highlighted) => result += highlighted.as_str()
					}
				}
			}
			result += "</code></a>";
		}

		Ok(result)
	}
}

impl Cached for Code
{
    type Key = String;
    type Value = String;

    fn sql_table() -> &'static str {
		"CREATE TABLE IF NOT EXISTS cached_code (
				digest	     TEXT PRIMARY KEY,
				highlighted  BLOB NOT NULL);"
    }

    fn sql_get_query() -> &'static str {
		"SELECT highlighted FROM cached_code WHERE digest = (?1)"
    }

    fn sql_insert_query() -> &'static str {
		"INSERT INTO cached_code (digest, highlighted) VALUES (?1, ?2)"
    }

    fn key(&self) -> <Self as Cached>::Key {
		let mut hasher = Sha512::new();
		hasher.input((self.block as usize).to_be_bytes().as_slice());
		hasher.input((self.line_offset as usize).to_be_bytes().as_slice());
		self.theme.as_ref().map(|theme| hasher.input(theme.as_bytes()));
		self.name.as_ref().map(|name| hasher.input(name.as_bytes()));
		hasher.input(self.language.as_bytes());
		hasher.input(self.code.as_bytes());

		hasher.result_str()
    }
}

impl Element for Code {
    fn location(&self) -> &Token { &self.location }

    fn kind(&self) -> ElemKind { if self.block == CodeKind::Inline { ElemKind::Inline } else { ElemKind::Block } }

    fn element_name(&self) -> &'static str { "Code Block" }

    fn to_string(&self) -> String { format!("{self:#?}") }

    fn compile(&self, compiler: &Compiler, _document: &Document)
		-> Result<String, String> {

		match compiler.target()
		{
			Target::HTML => {
				static CACHE_INIT : Once = Once::new();
				CACHE_INIT.call_once(|| if let Some(mut con) = compiler.cache() {
					if let Err(e) = Code::init(&mut con)
					{
						eprintln!("Unable to create cache table: {e}");
					}
				});

				if let Some(mut con) = compiler.cache()
				{
					match self.cached(&mut con, |s| s.highlight_html(compiler))
					{
						Ok(s) => Ok(s),
						Err(e) => match e
						{
							CachedError::SqlErr(e) => Err(format!("Querying the cache failed: {e}")),
							CachedError::GenErr(e) => Err(e)
						}
					}
				}
				else
				{
					self.highlight_html(compiler)
				}
			}
			Target::LATEX => { todo!("") }
		}
    }
}

pub struct CodeRule {
	re: [Regex; 2],
	properties: PropertyParser,
}

impl CodeRule {
	pub fn new() -> Self {
		let mut props = HashMap::new();
		props.insert("line_offset".to_string(),
			Property::new(
				true,
				"Line number offset".to_string(),
					Some("1".to_string())));
		Self {
			re: [
				Regex::new(r"(?:^|\n)```(?:\[((?:\\.|[^\\\\])*?)\])?(.*?)(?:,(.*))?\n((?:\\(?:.|\n)|[^\\\\])*?)```").unwrap(),
				Regex::new(r"``(?:\[((?:\\.|[^\[\]\\])*?)\])?(?:(.*)(?:\n|,))?((?:\\(?:.|\n)|[^\\\\])*?)``").unwrap(),
			],
			properties: PropertyParser::new(props)
		}
	}
}

impl RegexRule for CodeRule
{
    fn name(&self) -> &'static str { "Code" }

    fn regexes(&self) -> &[regex::Regex] { &self.re }

    fn on_regex_match(&self, index: usize, parser: &dyn Parser, document: &Document, token: Token, matches: Captures)
		-> Vec<Report<'_, (Rc<dyn Source>, Range<usize>)>> {
		let mut reports = vec![];

		let properties = match matches.get(1)
		{
			None => match self.properties.default() {
				Ok(properties) => properties,
				Err(e) => {
					reports.push(
						Report::build(ReportKind::Error, token.source(), token.start())
						.with_message("Invalid code")
						.with_label(
							Label::new((token.source().clone(), token.range.clone()))
							.with_message(format!("Code is missing properties: {e}"))
							.with_color(parser.colors().error))
						.finish());
						return reports;
				},
			}
			Some(props) => {
				let processed = util::process_escaped('\\', "]",
					props.as_str().trim_start().trim_end());
				match self.properties.parse(processed.as_str())
				{
					Err(e) => {
						reports.push(
							Report::build(ReportKind::Error, token.source(), props.start())
							.with_message("Invalid Code Properties")
							.with_label(
								Label::new((token.source().clone(), props.range()))
								.with_message(e)
								.with_color(parser.colors().error))
							.finish());
						return reports;
					}
					Ok(properties) => properties
				}
			}
		};
		
		let code_lang = match matches.get(2)
		{
			None => "Plain Text".to_string(),
			Some(lang) => {
				let code_lang = lang.as_str().trim_end().trim_start().to_string();
				if code_lang.is_empty()
				{
					reports.push(
						Report::build(ReportKind::Error, token.source(), lang.start())
						.with_message("Missing code language")
						.with_label(
							Label::new((token.source().clone(), lang.range()))
							.with_message("No language specified")
							.with_color(parser.colors().error))
						.finish());

					return reports;
				}
				
				// TODO: validate language

				code_lang
			}
		};

		let mut code_content = if index == 0
		{ util::process_escaped('\\',"```", matches.get(4).unwrap().as_str()) }
		else
		{ util::process_escaped('\\',"``", matches.get(3).unwrap().as_str()) };
		if code_content.bytes().last() == Some('\n' as u8) // Remove newline
		{
			code_content.pop();
		}

		if code_content.is_empty()
		{
			reports.push(
				Report::build(ReportKind::Error, token.source(), token.start())
				.with_message("Missing code content")
				.with_label(
					Label::new((token.source().clone(), token.range.clone()))
					.with_message("Code content cannot be empty")
					.with_color(parser.colors().error))
				.finish());
			return reports;
		}

		let theme = document.get_variable("code.theme")
			.and_then(|(_doc, var)| Some(var.to_string()));

		if index == 0 // Block
		{
			let code_name = matches.get(3)
				.and_then(|name| {
					let code_name = name.as_str().trim_end().trim_start().to_string();
					(!code_name.is_empty()).then_some(code_name)
				});
			let line_offset = match properties.get("line_offset",
				|prop, value| value.parse::<usize>().map_err(|e| (prop, e)))
			{
				Ok((_prop, offset)) => offset,
				Err((prop, e)) => {
					reports.push(
						Report::build(ReportKind::Error, token.source(), token.start())
						.with_message("Invalid Code Property")
						.with_label(
							Label::new((token.source().clone(), token.start()+1..token.end()))
							.with_message(format!("Property `line_offset: {}` cannot be converted: {}",
									prop.fg(parser.colors().info),
									e.fg(parser.colors().error)))
							.with_color(parser.colors().warning))
						.finish());
						return reports;
				}
			};

			parser.push(document, Box::new(
					Code::new(
						token.clone(),
						CodeKind::FullBlock,
						code_lang,
						code_name,
						code_content,
						theme,
						line_offset
					)
			));
		}
		else // Maybe inline
		{
			let block = if code_content.contains('\n') { CodeKind::MiniBlock }
			else { CodeKind::Inline };

			parser.push(document, Box::new(
					Code::new(
						token.clone(),
						block,
						code_lang,
						None,
						code_content,
						theme,
						1,
					)
			));
		}

		reports
    }
}