pub mod expr;

pub use expr::{BinaryExpression, Expr, SExpr};

use crate::typing::Type;

use ariadne;
use std::{fmt::Display, path::Path};

#[derive(Debug, PartialEq, Clone)]
pub enum BinaryOperator {
    // Logic
    And,
    Or,
    // Arithmetic
    Add,
    Sub,
    Mul,
    Div,
    Modulo,
    Equal,
    NotEqual,
}

impl Display for BinaryOperator {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.write_str(match self {
            BinaryOperator::And => "&&",
            BinaryOperator::Or => "||",
            BinaryOperator::Add => "+",
            BinaryOperator::Sub => "-",
            BinaryOperator::Mul => "*",
            BinaryOperator::Div => "/",
            BinaryOperator::Modulo => "%",
            BinaryOperator::Equal => "==",
            BinaryOperator::NotEqual => "!=",
        })
    }
}

#[derive(Debug, PartialEq, Copy, Clone)]
pub enum UnaryOperator {
    Not,
}

pub type Identifier = String;

pub type SourceId = u32;

#[derive(Debug, PartialEq, Clone, Copy)]
pub struct Span {
    pub source: SourceId,
    pub start: usize,
    pub end: usize,
}

impl ariadne::Span for Span {
    type SourceId = SourceId;

    fn source(&self) -> &Self::SourceId {
        &self.source
    }

    fn start(&self) -> usize {
        self.start
    }

    fn end(&self) -> usize {
        self.end
    }
}

#[derive(Debug, PartialEq, Clone, Default, Eq, Hash)]
pub struct ModulePath {
    components: Vec<String>,
}

impl ModulePath {
    pub fn concat(lhs: &ModulePath, rhs: &ModulePath) -> ModulePath {
        ModulePath {
            components: Vec::from_iter(
                lhs.components
                    .iter()
                    .chain(rhs.components.iter())
                    .map(Clone::clone),
            ),
        }
    }
}

impl std::fmt::Display for ModulePath {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.write_fmt(format_args!("{}", self.components.join("::")))
    }
}

impl From<&Path> for ModulePath {
    fn from(path: &Path) -> Self {
        let meta = std::fs::metadata(path).unwrap();
        ModulePath {
            components: path
                .components()
                .map(|component| match component {
                    std::path::Component::Normal(n) => {
                        if meta.is_file() {
                            n.to_str().unwrap().split('.').nth(0).unwrap().to_string()
                        } else if meta.is_dir() {
                            n.to_str().unwrap().to_string()
                        } else {
                            // XXX: symlinks?
                            unreachable!()
                        }
                    }
                    _ => unreachable!(),
                })
                .collect(),
        }
    }
}

impl From<&str> for ModulePath {
    fn from(string: &str) -> Self {
        ModulePath {
            components: string.split("::").map(|c| c.to_string()).collect(),
        }
    }
}

#[derive(Eq, PartialEq, Debug)]
pub struct Import(pub String);

#[derive(Debug, PartialEq)]
pub struct ReturnStatement {
    pub expr: Option<SExpr>,
    pub span: Span,
}

#[derive(Debug, PartialEq)]
pub enum Statement {
    DeclareStatement {
        lhs: Identifier,
        rhs: Box<SExpr>,
        span: Span,
    },
    AssignStatement {
        lhs: Identifier,
        rhs: Box<SExpr>,
        span: Span,
    },
    ReturnStatement(ReturnStatement),
    CallStatement {
        call: Box<Call>,
        span: Span,
    },
    UseStatement {
        import: Box<Import>,
        span: Span,
    },
    IfStatement {
        condition: Box<SExpr>,
        then_block: Box<Block>,
        span: Span,
    },
    WhileStatement {
        condition: Box<SExpr>,
        loop_block: Box<Block>,
        span: Span,
    },
}

#[derive(Debug, PartialEq)]
pub struct Block {
    pub statements: Vec<Statement>,
    pub value: Option<SExpr>,
    pub typ: Type,
    pub span: Option<Span>,
}

impl Block {
    pub fn empty() -> Block {
        Block {
            typ: Type::Unit,
            statements: Vec::with_capacity(0),
            value: None,
            span: None,
        }
    }
}

#[derive(Debug, PartialEq)]
pub enum Definition {
    FunctionDefinition(FunctionDefinition),
}

#[derive(Debug, PartialEq)]
pub struct FunctionDefinition {
    pub name: Identifier,
    pub parameters: Vec<Parameter>,
    pub return_type: Option<Type>,
    pub return_type_span: Option<Span>,
    pub body: Box<Block>,
    pub span: Span,
}

#[derive(Debug, PartialEq, Default)]
pub struct Module {
    pub file: Option<std::path::PathBuf>,
    pub path: ModulePath,
    pub functions: Vec<FunctionDefinition>,
    pub imports: Vec<Import>,
}

impl Module {
    pub fn new(path: ModulePath) -> Self {
        Self {
            path,
            ..Default::default()
        }
    }

    pub fn full_func_path(&self, func: usize) -> ModulePath {
        ModulePath::concat(
            &self.path,
            &ModulePath::from(self.functions[func].name.as_str()),
        )
    }
}

#[derive(Debug, PartialEq)]
pub struct Call {
    pub callee: Box<SExpr>,
    pub args: Vec<SExpr>,
    pub typ: Type,
}

#[derive(Debug, PartialEq)]
pub struct Parameter {
    pub name: Identifier,
    pub typ: Type,
}