use hir::db::HirDatabase;
use ra_syntax::{ast::AstNode, ast::Literal, TextRange, TextUnit};
use rustc_lexer;

use crate::{Assist, AssistCtx, AssistId};

pub(crate) fn make_raw_string(mut ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
    let literal = ctx.node_at_offset::<Literal>()?;
    if literal.token().kind() != ra_syntax::SyntaxKind::STRING {
        return None;
    }
    let token = literal.token();
    let text = token.text().as_str();
    let usual_string_range = find_usual_string_range(text)?;
    ctx.add_action(AssistId("make_raw_string"), "make raw string", |edit| {
        edit.target(literal.syntax().text_range());
        let start_of_inside = usual_string_range.start().to_usize() + 1;
        let end_of_inside = usual_string_range.end().to_usize();
        let inside_str = &text[start_of_inside..end_of_inside];
        let mut unescaped = String::with_capacity(inside_str.len());
        let mut error = Ok(());
        rustc_lexer::unescape::unescape_str(inside_str, &mut |_, unescaped_char| {
            match unescaped_char {
                Ok(c) => unescaped.push(c),
                Err(_) => error = Err(()),
            }
        });
        if error.is_err() {
            eprintln!("Error unescaping string");
        } else {
            edit.replace(literal.syntax().text_range(), format!("r#\"{}\"#", unescaped));
        }
    });
    ctx.build()
}

fn find_usual_string_range(s: &str) -> Option<TextRange> {
    Some(TextRange::from_to(
        TextUnit::from(s.find('"')? as u32),
        TextUnit::from(s.rfind('"')? as u32),
    ))
}

pub(crate) fn make_usual_string(mut ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
    let literal = ctx.node_at_offset::<Literal>()?;
    if literal.token().kind() != ra_syntax::SyntaxKind::RAW_STRING {
        return None;
    }
    let token = literal.token();
    let text = token.text().as_str();
    let usual_string_range = find_usual_string_range(text)?;
    ctx.add_action(AssistId("make_usual_string"), "make usual string", |edit| {
        edit.target(literal.syntax().text_range());
        // parse inside string to escape `"`
        let start_of_inside = usual_string_range.start().to_usize() + 1;
        let end_of_inside = usual_string_range.end().to_usize();
        let inside_str = &text[start_of_inside..end_of_inside];
        let escaped = inside_str.escape_default().to_string();
        edit.replace(literal.syntax().text_range(), format!("\"{}\"", escaped));
    });
    ctx.build()
}

pub(crate) fn add_hash(mut ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
    let literal = ctx.node_at_offset::<Literal>()?;
    if literal.token().kind() != ra_syntax::SyntaxKind::RAW_STRING {
        return None;
    }
    ctx.add_action(AssistId("add_hash"), "add hash to raw string", |edit| {
        edit.target(literal.syntax().text_range());
        edit.insert(literal.syntax().text_range().start() + TextUnit::of_char('r'), "#");
        edit.insert(literal.syntax().text_range().end(), "#");
    });
    ctx.build()
}

pub(crate) fn remove_hash(mut ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
    let literal = ctx.node_at_offset::<Literal>()?;
    if literal.token().kind() != ra_syntax::SyntaxKind::RAW_STRING {
        return None;
    }
    let token = literal.token();
    let text = token.text().as_str();
    if text.starts_with("r\"") {
        // no hash to remove
        return None;
    }
    ctx.add_action(AssistId("remove_hash"), "remove hash from raw string", |edit| {
        edit.target(literal.syntax().text_range());
        let result = &text[2..text.len() - 1];
        let result = if result.starts_with("\"") {
            // no more hash, escape
            let internal_str = &result[1..result.len() - 1];
            format!("\"{}\"", internal_str.escape_default().to_string())
        } else {
            result.to_owned()
        };
        edit.replace(literal.syntax().text_range(), format!("r{}", result));
    });
    ctx.build()
}

#[cfg(test)]
mod test {
    use super::*;
    use crate::helpers::{check_assist, check_assist_not_applicable, check_assist_target};

    #[test]
    fn make_raw_string_target() {
        check_assist_target(
            make_raw_string,
            r#"
            fn f() {
                let s = <|>"random\nstring";
            }
            "#,
            r#""random\nstring""#,
        );
    }

    #[test]
    fn make_raw_string_works() {
        check_assist(
            make_raw_string,
            r#"
            fn f() {
                let s = <|>"random\nstring";
            }
            "#,
            r##"
            fn f() {
                let s = <|>r#"random
string"#;
            }
            "##,
        )
    }

    #[test]
    fn make_raw_string_nothing_to_unescape_works() {
        check_assist(
            make_raw_string,
            r#"
            fn f() {
                let s = <|>"random string";
            }
            "#,
            r##"
            fn f() {
                let s = <|>r#"random string"#;
            }
            "##,
        )
    }

    #[test]
    fn add_hash_target() {
        check_assist_target(
            add_hash,
            r#"
            fn f() {
                let s = <|>r"random string";
            }
            "#,
            r#"r"random string""#,
        );
    }

    #[test]
    fn add_hash_works() {
        check_assist(
            add_hash,
            r#"
            fn f() {
                let s = <|>r"random string";
            }
            "#,
            r##"
            fn f() {
                let s = <|>r#"random string"#;
            }
            "##,
        )
    }

    #[test]
    fn add_more_hash_works() {
        check_assist(
            add_hash,
            r##"
            fn f() {
                let s = <|>r#"random"string"#;
            }
            "##,
            r###"
            fn f() {
                let s = <|>r##"random"string"##;
            }
            "###,
        )
    }

    #[test]
    fn add_hash_not_works() {
        check_assist_not_applicable(
            add_hash,
            r#"
            fn f() {
                let s = <|>"random string";
            }
            "#,
        );
    }

    #[test]
    fn remove_hash_target() {
        check_assist_target(
            remove_hash,
            r##"
            fn f() {
                let s = <|>r#"random string"#;
            }
            "##,
            r##"r#"random string"#"##,
        );
    }

    #[test]
    fn remove_hash_works() {
        check_assist(
            remove_hash,
            r##"
            fn f() {
                let s = <|>r#"random string"#;
            }
            "##,
            r#"
            fn f() {
                let s = <|>r"random string";
            }
            "#,
        )
    }

    #[test]
    fn remove_hash_with_quote_works() {
        check_assist(
            remove_hash,
            r##"
            fn f() {
                let s = <|>r#"random"str"ing"#;
            }
            "##,
            r#"
            fn f() {
                let s = <|>r"random\"str\"ing";
            }
            "#,
        )
    }

    #[test]
    fn remove_more_hash_works() {
        check_assist(
            remove_hash,
            r###"
            fn f() {
                let s = <|>r##"random string"##;
            }
            "###,
            r##"
            fn f() {
                let s = <|>r#"random string"#;
            }
            "##,
        )
    }

    #[test]
    fn remove_hash_not_works() {
        check_assist_not_applicable(
            remove_hash,
            r#"
            fn f() {
                let s = <|>"random string";
            }
            "#,
        );
    }

    #[test]
    fn remove_hash_no_hash_not_works() {
        check_assist_not_applicable(
            remove_hash,
            r#"
            fn f() {
                let s = <|>r"random string";
            }
            "#,
        );
    }

    #[test]
    fn make_usual_string_target() {
        check_assist_target(
            make_usual_string,
            r##"
            fn f() {
                let s = <|>r#"random string"#;
            }
            "##,
            r##"r#"random string"#"##,
        );
    }

    #[test]
    fn make_usual_string_works() {
        check_assist(
            make_usual_string,
            r##"
            fn f() {
                let s = <|>r#"random string"#;
            }
            "##,
            r#"
            fn f() {
                let s = <|>"random string";
            }
            "#,
        )
    }

    #[test]
    fn make_usual_string_with_quote_works() {
        check_assist(
            make_usual_string,
            r##"
            fn f() {
                let s = <|>r#"random"str"ing"#;
            }
            "##,
            r#"
            fn f() {
                let s = <|>"random\"str\"ing";
            }
            "#,
        )
    }

    #[test]
    fn make_usual_string_more_hash_works() {
        check_assist(
            make_usual_string,
            r###"
            fn f() {
                let s = <|>r##"random string"##;
            }
            "###,
            r##"
            fn f() {
                let s = <|>"random string";
            }
            "##,
        )
    }

    #[test]
    fn make_usual_string_not_works() {
        check_assist_not_applicable(
            make_usual_string,
            r#"
            fn f() {
                let s = <|>"random string";
            }
            "#,
        );
    }
}