use hir::{db::AstDatabase, InFile};
use ide_assists::Assist;
use ide_db::base_db::FilePosition;
use syntax::AstNode;

use crate::{
    diagnostics::{unresolved_fix, Diagnostic, DiagnosticsContext},
    references::rename::rename_with_semantics,
    Severity,
};

// Diagnostic: incorrect-ident-case
//
// This diagnostic is triggered if an item name doesn't follow https://doc.rust-lang.org/1.0.0/style/style/naming/README.html[Rust naming convention].
pub(super) fn incorrect_case(ctx: &DiagnosticsContext<'_>, d: &hir::IncorrectCase) -> Diagnostic {
    Diagnostic::new(
        "incorrect-ident-case",
        format!(
            "{} `{}` should have {} name, e.g. `{}`",
            d.ident_type, d.ident_text, d.expected_case, d.suggested_text
        ),
        ctx.sema.diagnostics_display_range(InFile::new(d.file, d.ident.clone().into())).range,
    )
    .severity(Severity::WeakWarning)
    .with_fixes(fixes(ctx, d))
}

fn fixes(ctx: &DiagnosticsContext<'_>, d: &hir::IncorrectCase) -> Option<Vec<Assist>> {
    let root = ctx.sema.db.parse_or_expand(d.file)?;
    let name_node = d.ident.to_node(&root);

    let name_node = InFile::new(d.file, name_node.syntax());
    let frange = name_node.original_file_range(ctx.sema.db);
    let file_position = FilePosition { file_id: frange.file_id, offset: frange.range.start() };

    let label = format!("Rename to {}", d.suggested_text);
    let mut res = unresolved_fix("change_case", &label, frange.range);
    if ctx.resolve.should_resolve(&res.id) {
        let source_change = rename_with_semantics(&ctx.sema, file_position, &d.suggested_text);
        res.source_change = Some(source_change.ok().unwrap_or_default());
    }

    Some(vec![res])
}

#[cfg(test)]
mod change_case {
    use crate::{
        diagnostics::tests::{check_diagnostics, check_fix},
        fixture, AssistResolveStrategy, DiagnosticsConfig,
    };

    #[test]
    fn test_rename_incorrect_case() {
        check_fix(
            r#"
pub struct test_struct$0 { one: i32 }

pub fn some_fn(val: test_struct) -> test_struct {
    test_struct { one: val.one + 1 }
}
"#,
            r#"
pub struct TestStruct { one: i32 }

pub fn some_fn(val: TestStruct) -> TestStruct {
    TestStruct { one: val.one + 1 }
}
"#,
        );

        check_fix(
            r#"
pub fn some_fn(NonSnakeCase$0: u8) -> u8 {
    NonSnakeCase
}
"#,
            r#"
pub fn some_fn(non_snake_case: u8) -> u8 {
    non_snake_case
}
"#,
        );

        check_fix(
            r#"
pub fn SomeFn$0(val: u8) -> u8 {
    if val != 0 { SomeFn(val - 1) } else { val }
}
"#,
            r#"
pub fn some_fn(val: u8) -> u8 {
    if val != 0 { some_fn(val - 1) } else { val }
}
"#,
        );

        check_fix(
            r#"
fn some_fn() {
    let whatAWeird_Formatting$0 = 10;
    another_func(whatAWeird_Formatting);
}
"#,
            r#"
fn some_fn() {
    let what_a_weird_formatting = 10;
    another_func(what_a_weird_formatting);
}
"#,
        );
    }

    #[test]
    fn test_uppercase_const_no_diagnostics() {
        check_diagnostics(
            r#"
fn foo() {
    const ANOTHER_ITEM$0: &str = "some_item";
}
"#,
        );
    }

    #[test]
    fn test_rename_incorrect_case_struct_method() {
        check_fix(
            r#"
pub struct TestStruct;

impl TestStruct {
    pub fn SomeFn$0() -> TestStruct {
        TestStruct
    }
}
"#,
            r#"
pub struct TestStruct;

impl TestStruct {
    pub fn some_fn() -> TestStruct {
        TestStruct
    }
}
"#,
        );
    }

    #[test]
    fn test_single_incorrect_case_diagnostic_in_function_name_issue_6970() {
        let input = r#"fn FOO$0() {}"#;
        let expected = r#"fn foo() {}"#;

        let (analysis, file_position) = fixture::position(input);
        let diagnostics = analysis
            .diagnostics(
                &DiagnosticsConfig::default(),
                AssistResolveStrategy::All,
                file_position.file_id,
            )
            .unwrap();
        assert_eq!(diagnostics.len(), 1);

        check_fix(input, expected);
    }
}