use std::mem;
use std::path::PathBuf;

use erg_common::Str;

use erg_common::astr::AtomicStr;
use erg_common::color::{RED, RESET, YELLOW};
use erg_common::error::{ErrorCore, ErrorKind, Location};
use erg_type::constructors::{and, builtin_mono, mono};
use erg_type::value::{EvalValueResult, TypeKind, TypeObj, ValueObj};
use erg_type::ValueArgs;

/// Requirement: Type, Impl := Type -> ClassType
pub fn class_func(
    mut args: ValueArgs,
    path: PathBuf,
    __name__: Option<Str>,
) -> EvalValueResult<ValueObj> {
    let require = args.remove_left_or_key("Requirement").ok_or_else(|| {
        ErrorCore::new(
            line!() as usize,
            ErrorKind::TypeError,
            Location::Unknown,
            AtomicStr::from(format!("{RED}Requirement{RESET} is not passed")),
            None,
        )
    })?;
    let require = if let Some(t) = require.as_type() {
        t
    } else {
        return Err(ErrorCore::new(
            line!() as usize,
            ErrorKind::TypeError,
            Location::Unknown,
            AtomicStr::from(format!(
                "non-type object {RED}{require}{RESET} is passed to {YELLOW}Requirement{RESET}",
            )),
            None,
        ));
    };
    let impls = args.remove_left_or_key("Impl");
    let impls = impls.map(|v| v.as_type().unwrap());
    let t = mono(path, __name__.unwrap_or(Str::ever("<Lambda>")));
    Ok(ValueObj::gen_t(TypeKind::Class, t, require, impls, None))
}

/// Super: ClassType, Impl := Type, Additional := Type -> ClassType
pub fn inherit_func(
    mut args: ValueArgs,
    path: PathBuf,
    __name__: Option<Str>,
) -> EvalValueResult<ValueObj> {
    let sup = args.remove_left_or_key("Super").ok_or_else(|| {
        ErrorCore::new(
            line!() as usize,
            ErrorKind::KeyError,
            Location::Unknown,
            AtomicStr::from(format!("{RED}Super{RESET} is not passed")),
            None,
        )
    })?;
    let sup = if let Some(t) = sup.as_type() {
        t
    } else {
        return Err(ErrorCore::new(
            line!() as usize,
            ErrorKind::TypeError,
            Location::Unknown,
            AtomicStr::from(format!(
                "non-class object {RED}{sup}{RESET} is passed to {YELLOW}Super{RESET}",
            )),
            None,
        ));
    };
    let impls = args.remove_left_or_key("Impl");
    let impls = impls.map(|v| v.as_type().unwrap());
    let additional = args.remove_left_or_key("Additional");
    let additional = additional.map(|v| v.as_type().unwrap());
    let t = mono(path, __name__.unwrap_or(Str::ever("<Lambda>")));
    Ok(ValueObj::gen_t(
        TypeKind::Subclass,
        t,
        sup,
        impls,
        additional,
    ))
}

/// Class: ClassType -> ClassType (with `InheritableType`)
/// This function is used by the compiler to mark a class as inheritable and does nothing in terms of actual operation.
pub fn inheritable_func(
    mut args: ValueArgs,
    _path: PathBuf,
    __name__: Option<Str>,
) -> EvalValueResult<ValueObj> {
    let class = args.remove_left_or_key("Class").ok_or_else(|| {
        ErrorCore::new(
            line!() as usize,
            ErrorKind::KeyError,
            Location::Unknown,
            AtomicStr::from(format!("{RED}Class{RESET} is not passed")),
            None,
        )
    })?;
    match class {
        ValueObj::Type(TypeObj::Generated(mut gen)) => {
            if let Some(typ) = &mut gen.impls {
                match typ.as_mut() {
                    TypeObj::Generated(gen) => {
                        gen.t = and(mem::take(&mut gen.t), builtin_mono("InheritableType"));
                    }
                    TypeObj::Builtin(t) => {
                        *t = and(mem::take(t), builtin_mono("InheritableType"));
                    }
                }
            } else {
                gen.impls = Some(Box::new(TypeObj::Builtin(builtin_mono("InheritableType"))));
            }
            Ok(ValueObj::Type(TypeObj::Generated(gen)))
        }
        _ => todo!(),
    }
}

/// Requirement: Type, Impl := Type -> TraitType
pub fn trait_func(
    mut args: ValueArgs,
    path: PathBuf,
    __name__: Option<Str>,
) -> EvalValueResult<ValueObj> {
    let require = args.remove_left_or_key("Requirement").ok_or_else(|| {
        ErrorCore::new(
            line!() as usize,
            ErrorKind::KeyError,
            Location::Unknown,
            AtomicStr::from(format!("{RED}Requirement{RESET} is not passed")),
            None,
        )
    })?;
    let require = if let Some(t) = require.as_type() {
        t
    } else {
        return Err(ErrorCore::new(
            line!() as usize,
            ErrorKind::TypeError,
            Location::Unknown,
            AtomicStr::from(format!(
                "non-type object {RED}{require}{RESET} is passed to {YELLOW}Requirement{RESET}",
            )),
            None,
        ));
    };
    let impls = args.remove_left_or_key("Impl");
    let impls = impls.map(|v| v.as_type().unwrap());
    let t = mono(path, __name__.unwrap_or(Str::ever("<Lambda>")));
    Ok(ValueObj::gen_t(TypeKind::Trait, t, require, impls, None))
}

/// Super: TraitType, Impl := Type, Additional := Type -> TraitType
pub fn subsume_func(
    mut args: ValueArgs,
    path: PathBuf,
    __name__: Option<Str>,
) -> EvalValueResult<ValueObj> {
    let sup = args.remove_left_or_key("Super").ok_or_else(|| {
        ErrorCore::new(
            line!() as usize,
            ErrorKind::KeyError,
            Location::Unknown,
            AtomicStr::from(format!("{RED}Super{RESET} is not passed")),
            None,
        )
    })?;
    let sup = if let Some(t) = sup.as_type() {
        t
    } else {
        return Err(ErrorCore::new(
            line!() as usize,
            ErrorKind::TypeError,
            Location::Unknown,
            AtomicStr::from(format!(
                "non-trait object {RED}{sup}{RESET} is passed to {YELLOW}Super{RESET}",
            )),
            None,
        ));
    };
    let impls = args.remove_left_or_key("Impl");
    let impls = impls.map(|v| v.as_type().unwrap());
    let additional = args.remove_left_or_key("Additional");
    let additional = additional.map(|v| v.as_type().unwrap());
    let t = mono(path, __name__.unwrap_or(Str::ever("<Lambda>")));
    Ok(ValueObj::gen_t(
        TypeKind::Subtrait,
        t,
        sup,
        impls,
        additional,
    ))
}