nml/src/elements/variable.rs

use mlua::{Function, Lua};
use regex::Regex;
use crate::{document::document::Document, parser::{parser::{Parser, ReportColors}, rule::RegexRule, source::{Source, Token}}};
use ariadne::{Report, Fmt, Label, ReportKind};
use crate::document::variable::{BaseVariable, PathVariable, Variable};
use std::{ops::Range, rc::Rc};

pub struct VariableRule {
	re: [Regex; 1],
    kinds: Vec<(String, String)>,
}

impl VariableRule {
	pub fn new() -> Self {
		Self {
            re: [Regex::new(r"(?:^|\n)@([^[:alpha:]])?(.*)=((?:\\\n|.)*)").unwrap()],
            kinds: vec![
                ("".into(), "Regular".into()),
                ("'".into(), "Path".into())
            ]
        }
	}

    pub fn make_variable(&self, colors: &ReportColors, location: Token, kind: usize, name: String, value: String) -> Result<Rc<dyn Variable>, String>
    {
        match self.kinds[kind].0.as_str()
        {
            "" => {
                Ok(Rc::new(BaseVariable::new(location, name, value)))
            }
            "'" => {
                match std::fs::canonicalize(value.as_str()) // TODO: not canonicalize
                {
                    Ok(path) => Ok(Rc::new(PathVariable::new(location, name, path))),
                    Err(e) => Err(format!("Unable to canonicalize path `{}`: {}",
                            value.fg(colors.highlight),
                            e.to_string()))
                }
            }
            _ => panic!("Unhandled variable kind")
        }
    }

    // Trim and check variable name for validity
    pub fn validate_name<'a>(colors: &ReportColors, original_name: &'a str) -> Result<&'a str, String>
    {
        let name = original_name.trim_start().trim_end();
        if name.contains("%")
        {
            return Err(format!("Name cannot contain '{}'",
                "%".fg(colors.info)));
        }
        return Ok(name);
    }

    pub fn validate_value(_colors: &ReportColors, original_value: &str) -> Result<String, String>
    {
		let mut escaped = 0usize;
		let mut result = String::new();
		for c in original_value.trim_start().trim_end().chars() {
			if c == '\\' { escaped += 1 }
			else if c == '\n' {
				match escaped {
					0 => return Err("Unknown error wile capturing variable".to_string()),
					// Remove '\n'
					1 => {},
					// Insert '\n'
					_ => {
						result.push(c);
						(0..escaped-2).for_each(|_| result.push('\\'));
					}
				}
				escaped = 0;
			}
			else {
				(0..escaped).for_each(|_| result.push('\\'));
				escaped = 0;
				result.push(c);
			}
		}
		(0..escaped).for_each(|_| result.push('\\'));

		Ok(result)
    }
}

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

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



	fn on_regex_match<'a>(&self, _: usize, parser: &dyn Parser, document: &'a dyn Document, token: Token, matches: regex::Captures) -> Vec<Report<'_, (Rc<dyn Source>, Range<usize>)>>
	{
		let mut result = vec![];
        // [Optional] variable kind
		let var_kind = match matches.get(1)
		{
			Some(kind) => {
                // Find kind
                let r = self.kinds.iter().enumerate().find(|(_i, (ref char, ref _name))| {
                    char == kind.as_str() });

                // Unknown kind specified
                if r.is_none()
                {
                    result.push(
                        Report::build(ReportKind::Error, token.source(), kind.start())
                        .with_message("Unknown variable kind")
                        .with_label(
                            Label::new((token.source(), kind.range()))
                            .with_message(format!("Variable kind `{}` is unknown",
                                    kind.as_str().fg(parser.colors().highlight)))
                            .with_color(parser.colors().error))
                        .with_help(format!("Leave empty for regular variables. Available variable kinds:{}",
                            self.kinds.iter().skip(1).fold("".to_string(), |acc, (char, name)| {
                                acc + format!("\n - `{}` : {}",
                                    char.fg(parser.colors().highlight),
                                    name.fg(parser.colors().info)).as_str()
                            })))
                        .finish());

                    return result;
                }

                r.unwrap().0
			}
			None => 0,
		};

        let var_name = match matches.get(2)
        {
            Some(name) => {
                match VariableRule::validate_name(&parser.colors(), name.as_str())
                {
                    Ok(var_name) => var_name,
                    Err(msg) => {
                        result.push(
                            Report::build(ReportKind::Error, token.source(), name.start())
                            .with_message("Invalid variable name")
                            .with_label(
                                Label::new((token.source(), name.range()))
                                .with_message(format!("Variable name `{}` is not allowed. {msg}",
                                        name.as_str().fg(parser.colors().highlight)))
                                .with_color(parser.colors().error))
                            .finish());

                        return result;
                    },
                }
            },
            _ => panic!("Unknown variable name")
        };

        let var_value = match matches.get(3)
        {
            Some(value) => {
                match VariableRule::validate_value(&parser.colors(), value.as_str())
                {
                    Ok(var_value) => var_value,
                    Err(msg ) => {
                        result.push(
                            Report::build(ReportKind::Error, token.source(), value.start())
                            .with_message("Invalid variable value")
                            .with_label(
                                Label::new((token.source(), value.range()))
                                .with_message(format!("Variable value `{}` is not allowed. {msg}",
                                        value.as_str().fg(parser.colors().highlight)))
                                .with_color(parser.colors().error))
                            .finish());

                        return result;
                    }
                }
            }
            _ => panic!("Invalid variable value")
        };

        match self.make_variable(&parser.colors(), token.clone(), var_kind, var_name.to_string(), var_value)
        {
            Ok(variable) => document.add_variable(variable),
            Err(msg) => {
                let m = matches.get(0).unwrap();
                result.push(
                    Report::build(ReportKind::Error, token.source(), m.start())
                    .with_message("Unable to create variable")
                    .with_label(
                        Label::new((token.source(), m.start()+1 .. m.end() ))
                        .with_message(format!("Unable to create variable `{}`. {}",
                                var_name.fg(parser.colors().highlight),
                                msg))
                        .with_color(parser.colors().error))
                    .finish());

                return result;
            }
        }

        return result;
	}

	// TODO
	fn lua_bindings<'lua>(&self, _lua: &'lua Lua) -> Vec<(String, Function<'lua>)> { vec![] }
}

pub struct VariableSubstitutionRule
{
	re: [Regex; 1],
}

impl VariableSubstitutionRule {
	pub fn new() -> Self {
		Self {
            re: [Regex::new(r"%(.*?)%").unwrap()],
        }
	}
}

impl RegexRule for VariableSubstitutionRule
{
    fn name(&self) -> &'static str { "Variable Substitution" }

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

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

        let variable = match matches.get(1)
        {
            Some(name) => {
                // Empty name
                if name.as_str().is_empty()
                {
                    result.push(
                        Report::build(ReportKind::Error, token.source(), name.start())
                        .with_message("Empty variable name")
                        .with_label(
                            Label::new((token.source(), matches.get(0).unwrap().range()))
                            .with_message(format!("Missing variable name for substitution"))
                            .with_color(parser.colors().error))
                        .finish());

                    return result;
                }
                // Leading spaces
                else if name.as_str().trim_start() != name.as_str()
                {
                    result.push(
                        Report::build(ReportKind::Error, token.source(), name.start())
                        .with_message("Invalid variable name")
                        .with_label(
                            Label::new((token.source(), name.range()))
                            .with_message(format!("Variable names contains leading spaces"))
                            .with_color(parser.colors().error))
                        .with_help("Remove leading spaces")
                        .finish());

                    return result;
                }
                // Trailing spaces
                else if name.as_str().trim_end() != name.as_str()
                {
                    result.push(
                        Report::build(ReportKind::Error, token.source(), name.start())
                        .with_message("Invalid variable name")
                        .with_label(
                            Label::new((token.source(), name.range()))
                            .with_message(format!("Variable names contains trailing spaces"))
                            .with_color(parser.colors().error))
                        .with_help("Remove trailing spaces")
                        .finish());

                    return result;
                }
				// Invalid name
                match VariableRule::validate_name(&parser.colors(), name.as_str())
                {
					Err(msg) =>
					{
						result.push(
							Report::build(ReportKind::Error, token.source(), name.start())
							.with_message("Invalid variable name")
							.with_label(
								Label::new((token.source(), name.range()))
								.with_message(msg)
								.with_color(parser.colors().error))
							.finish());

						return result;
					}
					_ => {},
                }
				
				// Get variable
                match document.get_variable(name.as_str())
                {
                    None => {
                        result.push(
                            Report::build(ReportKind::Error, token.source(), name.start())
                            .with_message("Unknown variable name")
                            .with_label(
                                Label::new((token.source(), name.range()))
                                .with_message(format!("Unable to find variable with name: `{}`",
                                        name.as_str().fg(parser.colors().highlight)))
                                .with_color(parser.colors().error))
                            .finish());
                        return result;
                    }
                    Some(var) => var,
                }
            },
            _ => panic!("Unknown error")
        };

		variable.parse(token, parser, document);

        return result;
    }

	// TODO
	fn lua_bindings<'lua>(&self, _lua: &'lua Lua) -> Vec<(String, Function<'lua>)> { vec![] }
}