pub mod abstract_tree;
pub mod built_in_functions;
pub mod context;
pub mod error;
pub mod lexer;
pub mod parser;
pub mod value;

use std::{cell::RefCell, ops::Range, rc::Rc, vec};

use abstract_tree::Type;
use ariadne::{Color, Fmt, Label, Report, ReportKind};
use context::Context;
use error::{Error, RuntimeError, TypeConflict, ValidationError};
use lexer::lex;
use parser::parse;
pub use value::Value;

pub fn interpret<'src>(source_id: &str, source: &str) -> Result<Option<Value>, InterpreterError> {
    let mut interpreter = Interpreter::new(Context::new());

    interpreter.run(Rc::new(source_id.to_string()), Rc::from(source))
}

pub fn interpret_without_std(
    source_id: &str,
    source: &str,
) -> Result<Option<Value>, InterpreterError> {
    let mut interpreter = Interpreter::new(Context::new());

    interpreter.run(Rc::new(source_id.to_string()), Rc::from(source))
}

pub struct Interpreter {
    context: Context,
    sources: Rc<RefCell<Vec<(Rc<String>, Rc<str>)>>>,
}

impl Interpreter {
    pub fn new(context: Context) -> Self {
        Interpreter {
            context,
            sources: Rc::new(RefCell::new(Vec::new())),
        }
    }

    pub fn run(
        &mut self,
        source_id: Rc<String>,
        source: Rc<str>,
    ) -> Result<Option<Value>, InterpreterError> {
        let tokens = lex(source.as_ref()).map_err(|errors| InterpreterError {
            source_id: source_id.clone(),
            errors,
        })?;
        let abstract_tree = parse(&tokens).map_err(|errors| InterpreterError {
            source_id: source_id.clone(),
            errors,
        })?;
        let value_option = abstract_tree
            .run(&self.context)
            .map_err(|errors| InterpreterError {
                source_id: source_id.clone(),
                errors,
            })?;

        self.sources.borrow_mut().push((source_id, source.into()));

        Ok(value_option)
    }

    pub fn run_all<T: IntoIterator<Item = (Rc<String>, Rc<str>)>>(
        &mut self,
        sources: T,
    ) -> Result<Option<Value>, InterpreterError> {
        let mut previous_value_option = None;

        for (source_id, source) in sources {
            previous_value_option = self.run(source_id.clone(), source)?;
        }

        Ok(previous_value_option)
    }

    pub fn load_std(&mut self) -> Result<Option<Value>, InterpreterError> {
        self.run_all([
            (
                Rc::new("std/io.ds".to_string()),
                Rc::from(include_str!("../../std/io.ds")),
            ),
            (
                Rc::new("std/thread.ds".to_string()),
                Rc::from(include_str!("../../std/thread.ds")),
            ),
        ])
    }

    pub fn sources(&self) -> vec::IntoIter<(Rc<String>, Rc<str>)> {
        self.sources.borrow().clone().into_iter()
    }
}

#[derive(Debug, PartialEq)]
pub struct InterpreterError {
    source_id: Rc<String>,
    errors: Vec<Error>,
}

impl InterpreterError {
    pub fn errors(&self) -> &Vec<Error> {
        &self.errors
    }
}

impl InterpreterError {
    pub fn build_reports<'a>(self) -> Vec<Report<'a, (Rc<String>, Range<usize>)>> {
        let mut reports = Vec::new();

        for error in self.errors {
            let (mut builder, validation_error, error_position) = match error {
            Error::Lex {
                expected,
                span,
                reason,
            } => {
                let description = if expected.is_empty() {
                    "Invalid character.".to_string()
                } else {
                    format!("Expected {expected}.")
                };

                (
                    Report::build(
                        ReportKind::Custom("Lexing Error", Color::Yellow),
                        self.source_id.clone(),
                        span.1,
                    )
                    .with_message(description)
                    .with_label(
                        Label::new((self.source_id.clone(), span.0..span.1))
                            .with_message(reason)
                            .with_color(Color::Red),
                    ),
                    None,
                    span.into(),
                )
            }
            Error::Parse {
                expected,
                span,
                reason,
            } => {
                let description = if expected.is_empty() {
                    "Invalid token.".to_string()
                } else {
                    format!("Expected {expected}.")
                };

                (
                    Report::build(
                        ReportKind::Custom("Parsing Error", Color::Yellow),
                        self.source_id.clone(),
                        span.1,
                    )
                    .with_message(description)
                    .with_label(
                        Label::new((self.source_id.clone(), span.0..span.1))
                            .with_message(reason)
                            .with_color(Color::Red),
                    ),
                    None,
                    span.into(),
                )
            }
            Error::Runtime { error, position } => (
                Report::build(
                    ReportKind::Custom("Runtime Error", Color::Red),
                    self.source_id.clone(),
                    position.1,
                )
                .with_message("An error occured that forced the program to exit.")
                .with_note(
                    "There may be unexpected side-effects because the program could not finish.",
                )
                .with_help(
                    "This is the interpreter's fault. Please submit a bug with this error message.",
                ),
                if let RuntimeError::ValidationFailure(validation_error) = error {
                    Some(validation_error)
                } else {
                    None
                },
                position,
            ),
            Error::Validation { error, position } => (
                Report::build(
                    ReportKind::Custom("Validation Error", Color::Magenta),
                    self.source_id.clone(),
                    position.1,
                )
                .with_message("The syntax is valid but this code is not sound.")
                .with_note("This error was detected by the interpreter before running the code."),
                Some(error),
                position,
            ),
        };

            let type_color = Color::Green;
            let identifier_color = Color::Blue;

            if let Some(validation_error) = validation_error {
                match validation_error {
                    ValidationError::ExpectedBoolean { actual, position } => {
                        builder.add_label(
                            Label::new((self.source_id.clone(), position.0..position.1))
                                .with_message(format!(
                                    "Expected {} but got {}.",
                                    "boolean".fg(type_color),
                                    actual.fg(type_color)
                                )),
                        );
                    }
                    ValidationError::ExpectedIntegerOrFloat(position) => {
                        builder.add_label(
                            Label::new((self.source_id.clone(), position.0..position.1))
                                .with_message(format!(
                                    "Expected {} or {}.",
                                    "integer".fg(type_color),
                                    "float".fg(type_color)
                                )),
                        );
                    }
                    ValidationError::RwLockPoison(_) => todo!(),
                    ValidationError::TypeCheck {
                        conflict,
                        actual_position,
                        expected_position: expected_postion,
                    } => {
                        let TypeConflict { actual, expected } = conflict;

                        builder.add_labels([
                            Label::new((
                                self.source_id.clone(),
                                expected_postion.0..expected_postion.1,
                            ))
                            .with_message(format!(
                                "Type {} established here.",
                                expected.fg(type_color)
                            )),
                            Label::new((
                                self.source_id.clone(),
                                actual_position.0..actual_position.1,
                            ))
                            .with_message(format!("Got type {} here.", actual.fg(type_color))),
                        ]);
                    }
                    ValidationError::VariableNotFound(identifier) => builder.add_label(
                        Label::new((self.source_id.clone(), error_position.0..error_position.1))
                            .with_message(format!(
                                "Variable {} does not exist in this context.",
                                identifier.fg(identifier_color)
                            )),
                    ),
                    ValidationError::CannotIndex { r#type, position } => builder.add_label(
                        Label::new((self.source_id.clone(), position.0..position.1)).with_message(
                            format!("Cannot index into a {}.", r#type.fg(type_color)),
                        ),
                    ),
                    ValidationError::CannotIndexWith {
                        collection_type,
                        collection_position,
                        index_type,
                        index_position,
                    } => {
                        builder = builder.with_message(format!(
                            "Cannot index into {} with {}.",
                            collection_type.clone().fg(type_color),
                            index_type.clone().fg(type_color)
                        ));

                        builder.add_labels([
                            Label::new((
                                self.source_id.clone(),
                                collection_position.0..collection_position.1,
                            ))
                            .with_message(format!(
                                "This has type {}.",
                                collection_type.fg(type_color),
                            )),
                            Label::new((
                                self.source_id.clone(),
                                index_position.0..index_position.1,
                            ))
                            .with_message(format!("This has type {}.", index_type.fg(type_color),)),
                        ])
                    }
                    ValidationError::InterpreterExpectedReturn(_) => todo!(),
                    ValidationError::ExpectedFunction { .. } => todo!(),
                    ValidationError::ExpectedValue(_) => todo!(),
                    ValidationError::PropertyNotFound { .. } => todo!(),
                    ValidationError::WrongArguments { .. } => todo!(),
                    ValidationError::ExpectedIntegerFloatOrString { actual, position } => {
                        builder = builder.with_message(format!(
                            "Expected an {}, {} or {}.",
                            Type::Integer.fg(type_color),
                            Type::Float.fg(type_color),
                            Type::String.fg(type_color)
                        ));

                        builder.add_labels([Label::new((
                            self.source_id.clone(),
                            position.0..position.1,
                        ))
                        .with_message(format!("This has type {}.", actual.fg(type_color),))])
                    }
                }
            }
            let report = builder.finish();

            reports.push(report);
        }

        reports
    }
}