/*
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 */

use dupe::Dupe;
use flow_parser::ast;
use flow_parser::ast::types::TypeInner;
use flow_parser::ast_visitor::AstVisitor;
use flow_parser::ast_visitor::map_expression_default;
use flow_parser::ast_visitor::map_program_default;
use flow_parser::ast_visitor::map_statement_default;
use flow_parser::ast_visitor::map_type_default;
use flow_parser::loc::Loc;

use crate::contains_mapper::ContainsMapper;

#[derive(PartialEq, Eq)]
enum Kind {
    DollarKeys,
}

struct Mapper {
    contains: ContainsMapper,
    kind: Kind,
}

impl AstVisitor<'_, Loc> for Mapper {
    fn normalize_loc(loc: &Loc) -> &Loc {
        loc
    }

    fn normalize_type(type_: &Loc) -> &Loc {
        type_
    }

    fn map_type_(&mut self, t: &ast::types::Type<Loc, Loc>) -> ast::types::Type<Loc, Loc> {
        match &**t {
            TypeInner::Generic { loc, inner }
                if self.contains.is_target(loc) && self.kind == Kind::DollarKeys =>
            {
                if let ast::types::generic::Identifier::Unqualified(id) = &inner.id {
                    if id.name.as_str() == "$Keys" {
                        if let Some(targs) = &inner.targs {
                            if targs.arguments.len() == 1 {
                                let targ = &targs.arguments[0];
                                return ast::types::Type::new(TypeInner::Keyof {
                                    loc: loc.dupe(),
                                    inner: std::sync::Arc::new(ast::types::Keyof {
                                        argument: targ.dupe(),
                                        comments: inner.comments.clone(),
                                    }),
                                });
                            }
                        }
                    }
                }
                map_type_default(self, t)
            }
            _ => map_type_default(self, t),
        }
    }

    fn map_program(&mut self, program: &ast::Program<Loc, Loc>) -> ast::Program<Loc, Loc> {
        if self.contains.should_map_program(program) {
            map_program_default(self, program)
        } else {
            program.clone()
        }
    }

    fn map_statement(
        &mut self,
        stmt: &ast::statement::Statement<Loc, Loc>,
    ) -> ast::statement::Statement<Loc, Loc> {
        if self.contains.should_map_statement(stmt) {
            map_statement_default(self, stmt)
        } else {
            stmt.dupe()
        }
    }

    fn map_expression(
        &mut self,
        expr: &ast::expression::Expression<Loc, Loc>,
    ) -> ast::expression::Expression<Loc, Loc> {
        if self.contains.should_map_expression(expr) {
            map_expression_default(self, expr)
        } else {
            expr.dupe()
        }
    }
}

pub fn convert_dollar_keys_type(ast: &ast::Program<Loc, Loc>, loc: Loc) -> ast::Program<Loc, Loc> {
    let mut mapper = Mapper {
        contains: ContainsMapper::new(loc),
        kind: Kind::DollarKeys,
    };
    mapper.map_program(ast)
}
