//! Defines `Fixture` -- a convenient way to describe the initial state of
//! rust-analyzer database from a single string.

use rustc_hash::FxHashMap;
use stdx::split1;

#[derive(Debug, Eq, PartialEq)]
pub struct Fixture {
    pub path: String,
    pub text: String,
    pub crate_name: Option<String>,
    pub deps: Vec<String>,
    pub cfg_atoms: Vec<String>,
    pub cfg_key_values: Vec<(String, String)>,
    pub edition: Option<String>,
    pub env: FxHashMap<String, String>,
}

impl Fixture {
    /// Parses text which looks like this:
    ///
    ///  ```not_rust
    ///  //- some meta
    ///  line 1
    ///  line 2
    ///  // - other meta
    ///  ```
    pub fn parse(ra_fixture: &str) -> Vec<Fixture> {
        let fixture = indent_first_line(ra_fixture);
        let margin = fixture_margin(&fixture);

        let mut lines = fixture
        .split('\n') // don't use `.lines` to not drop `\r\n`
        .enumerate()
        .filter_map(|(ix, line)| {
            if line.len() >= margin {
                assert!(line[..margin].trim().is_empty());
                let line_content = &line[margin..];
                if !line_content.starts_with("//-") {
                    assert!(
                        !line_content.contains("//-"),
                        r#"Metadata line {} has invalid indentation. All metadata lines need to have the same indentation.
The offending line: {:?}"#,
                        ix,
                        line
                    );
                }
                Some(line_content)
            } else {
                assert!(line.trim().is_empty());
                None
            }
        });

        let mut res: Vec<Fixture> = Vec::new();
        for line in lines.by_ref() {
            if line.starts_with("//-") {
                let meta = line["//-".len()..].trim().to_string();
                let meta = Fixture::parse_single(&meta);
                res.push(meta)
            } else if let Some(entry) = res.last_mut() {
                entry.text.push_str(line);
                entry.text.push('\n');
            }
        }
        res
    }

    //- /lib.rs crate:foo deps:bar,baz cfg:foo=a,bar=b env:OUTDIR=path/to,OTHER=foo
    fn parse_single(meta: &str) -> Fixture {
        let components = meta.split_ascii_whitespace().collect::<Vec<_>>();

        let path = components[0].to_string();
        assert!(path.starts_with("/"));

        let mut krate = None;
        let mut deps = Vec::new();
        let mut edition = None;
        let mut cfg_atoms = Vec::new();
        let mut cfg_key_values = Vec::new();
        let mut env = FxHashMap::default();
        for component in components[1..].iter() {
            let (key, value) = split1(component, ':').unwrap();
            match key {
                "crate" => krate = Some(value.to_string()),
                "deps" => deps = value.split(',').map(|it| it.to_string()).collect(),
                "edition" => edition = Some(value.to_string()),
                "cfg" => {
                    for entry in value.split(',') {
                        match split1(entry, '=') {
                            Some((k, v)) => cfg_key_values.push((k.to_string(), v.to_string())),
                            None => cfg_atoms.push(entry.to_string()),
                        }
                    }
                }
                "env" => {
                    for key in value.split(',') {
                        if let Some((k, v)) = split1(key, '=') {
                            env.insert(k.into(), v.into());
                        }
                    }
                }
                _ => panic!("bad component: {:?}", component),
            }
        }

        Fixture {
            path,
            text: String::new(),
            crate_name: krate,
            deps,
            cfg_atoms,
            cfg_key_values,
            edition,
            env,
        }
    }
}

/// Adjusts the indentation of the first line to the minimum indentation of the rest of the lines.
/// This allows fixtures to start off in a different indentation, e.g. to align the first line with
/// the other lines visually:
/// ```
/// let fixture = "//- /lib.rs
///                mod foo;
///                //- /foo.rs
///                fn bar() {}
/// ";
/// assert_eq!(fixture_margin(fixture),
/// "               //- /lib.rs
///                mod foo;
///                //- /foo.rs
///                fn bar() {}
/// ")
/// ```
fn indent_first_line(fixture: &str) -> String {
    if fixture.is_empty() {
        return String::new();
    }
    let mut lines = fixture.lines();
    let first_line = lines.next().unwrap();
    if first_line.contains("//-") {
        let rest = lines.collect::<Vec<_>>().join("\n");
        let fixed_margin = fixture_margin(&rest);
        let fixed_indent = fixed_margin - indent_len(first_line);
        format!("\n{}{}\n{}", " ".repeat(fixed_indent), first_line, rest)
    } else {
        fixture.to_owned()
    }
}

fn fixture_margin(fixture: &str) -> usize {
    fixture
        .lines()
        .filter(|it| it.trim_start().starts_with("//-"))
        .map(indent_len)
        .next()
        .expect("empty fixture")
}

fn indent_len(s: &str) -> usize {
    s.len() - s.trim_start().len()
}

#[test]
#[should_panic]
fn parse_fixture_checks_further_indented_metadata() {
    Fixture::parse(
        r"
        //- /lib.rs
          mod bar;

          fn foo() {}
          //- /bar.rs
          pub fn baz() {}
          ",
    );
}

#[test]
fn parse_fixture_can_handle_dedented_first_line() {
    let fixture = "//- /lib.rs
                   mod foo;
                   //- /foo.rs
                   struct Bar;
";
    assert_eq!(
        Fixture::parse(fixture),
        Fixture::parse(
            "//- /lib.rs
mod foo;
//- /foo.rs
struct Bar;
"
        )
    )
}

#[test]
fn parse_fixture_gets_full_meta() {
    let parsed = Fixture::parse(
        r"
    //- /lib.rs crate:foo deps:bar,baz cfg:foo=a,bar=b,atom env:OUTDIR=path/to,OTHER=foo
    mod m;
    ",
    );
    assert_eq!(1, parsed.len());

    let meta = &parsed[0];
    assert_eq!("mod m;\n\n", meta.text);

    assert_eq!("foo", meta.crate_name.as_ref().unwrap());
    assert_eq!("/lib.rs", meta.path);
    assert_eq!(2, meta.env.len());
}