//! SCIP generator

use std::{
    collections::{HashMap, HashSet},
    time::Instant,
};

use crate::line_index::{LineEndings, LineIndex, OffsetEncoding};
use hir::Name;
use ide::{
    LineCol, MonikerDescriptorKind, MonikerResult, StaticIndex, StaticIndexedFile, TextRange,
    TokenId,
};
use ide_db::LineIndexDatabase;
use project_model::{CargoConfig, ProjectManifest, ProjectWorkspace};
use scip::types as scip_types;
use std::env;

use crate::cli::{
    flags,
    load_cargo::{load_workspace, LoadCargoConfig},
    Result,
};

impl flags::Scip {
    pub fn run(self) -> Result<()> {
        eprintln!("Generating SCIP start...");
        let now = Instant::now();
        let cargo_config = CargoConfig::default();

        let no_progress = &|s| (eprintln!("rust-analyzer: Loading {}", s));
        let load_cargo_config = LoadCargoConfig {
            load_out_dirs_from_check: true,
            with_proc_macro: true,
            prefill_caches: true,
        };
        let path = vfs::AbsPathBuf::assert(env::current_dir()?.join(&self.path));
        let rootpath = path.normalize();
        let manifest = ProjectManifest::discover_single(&path)?;

        let workspace = ProjectWorkspace::load(manifest, &cargo_config, no_progress)?;

        let (host, vfs, _) = load_workspace(workspace, &load_cargo_config)?;
        let db = host.raw_database();
        let analysis = host.analysis();

        let si = StaticIndex::compute(&analysis);

        let mut index = scip_types::Index {
            metadata: Some(scip_types::Metadata {
                version: scip_types::ProtocolVersion::UnspecifiedProtocolVersion.into(),
                tool_info: Some(scip_types::ToolInfo {
                    name: "rust-analyzer".to_owned(),
                    version: "0.1".to_owned(),
                    arguments: vec![],
                    ..Default::default()
                })
                .into(),
                project_root: format!(
                    "file://{}",
                    path.normalize()
                        .as_os_str()
                        .to_str()
                        .ok_or(anyhow::anyhow!("Unable to normalize project_root path"))?
                        .to_string()
                ),
                text_document_encoding: scip_types::TextEncoding::UTF8.into(),
                ..Default::default()
            })
            .into(),
            ..Default::default()
        };

        let mut symbols_emitted: HashSet<TokenId> = HashSet::default();
        let mut tokens_to_symbol: HashMap<TokenId, String> = HashMap::new();

        for file in si.files {
            let mut local_count = 0;
            let mut new_local_symbol = || {
                let new_symbol = scip::types::Symbol::new_local(local_count);
                local_count += 1;

                new_symbol
            };

            let StaticIndexedFile { file_id, tokens, .. } = file;
            let relative_path = match get_relative_filepath(&vfs, &rootpath, file_id) {
                Some(relative_path) => relative_path,
                None => continue,
            };

            let line_index = LineIndex {
                index: db.line_index(file_id),
                encoding: OffsetEncoding::Utf8,
                endings: LineEndings::Unix,
            };

            let mut doc = scip_types::Document {
                relative_path,
                language: "rust".to_string(),
                ..Default::default()
            };

            tokens.into_iter().for_each(|(range, id)| {
                let token = si.tokens.get(id).unwrap();

                let mut occurrence = scip_types::Occurrence::default();
                occurrence.range = text_range_to_scip_range(&line_index, range);
                occurrence.symbol = match tokens_to_symbol.get(&id) {
                    Some(symbol) => symbol.clone(),
                    None => {
                        let symbol = match &token.moniker {
                            Some(moniker) => moniker_to_symbol(&moniker),
                            None => new_local_symbol(),
                        };

                        let symbol = scip::symbol::format_symbol(symbol);
                        tokens_to_symbol.insert(id, symbol.clone());
                        symbol
                    }
                };

                if let Some(def) = token.definition {
                    if def.range == range {
                        occurrence.symbol_roles |= scip_types::SymbolRole::Definition as i32;
                    }

                    if !symbols_emitted.contains(&id) {
                        symbols_emitted.insert(id);

                        let mut symbol_info = scip_types::SymbolInformation::default();
                        symbol_info.symbol = occurrence.symbol.clone();
                        if let Some(hover) = &token.hover {
                            if !hover.markup.as_str().is_empty() {
                                symbol_info.documentation = vec![hover.markup.as_str().to_string()];
                            }
                        }

                        doc.symbols.push(symbol_info)
                    }
                }

                doc.occurrences.push(occurrence);
            });

            if doc.occurrences.is_empty() {
                continue;
            }

            index.documents.push(doc);
        }

        scip::write_message_to_file("index.scip", index)
            .map_err(|err| anyhow::anyhow!("Failed to write scip to file: {}", err))?;

        eprintln!("Generating SCIP finished {:?}", now.elapsed());
        Ok(())
    }
}

fn get_relative_filepath(
    vfs: &vfs::Vfs,
    rootpath: &vfs::AbsPathBuf,
    file_id: ide::FileId,
) -> Option<String> {
    Some(vfs.file_path(file_id).as_path()?.strip_prefix(&rootpath)?.as_ref().to_str()?.to_string())
}

// SCIP Ranges have a (very large) optimization that ranges if they are on the same line
// only encode as a vector of [start_line, start_col, end_col].
//
// This transforms a line index into the optimized SCIP Range.
fn text_range_to_scip_range(line_index: &LineIndex, range: TextRange) -> Vec<i32> {
    let LineCol { line: start_line, col: start_col } = line_index.index.line_col(range.start());
    let LineCol { line: end_line, col: end_col } = line_index.index.line_col(range.end());

    if start_line == end_line {
        vec![start_line as i32, start_col as i32, end_col as i32]
    } else {
        vec![start_line as i32, start_col as i32, end_line as i32, end_col as i32]
    }
}

fn new_descriptor_str(
    name: &str,
    suffix: scip_types::descriptor::Suffix,
) -> scip_types::Descriptor {
    scip_types::Descriptor {
        name: name.to_string(),
        disambiguator: "".to_string(),
        suffix: suffix.into(),
        ..Default::default()
    }
}

fn new_descriptor(name: Name, suffix: scip_types::descriptor::Suffix) -> scip_types::Descriptor {
    let mut name = name.to_string();
    if name.contains("'") {
        name = format!("`{}`", name);
    }

    new_descriptor_str(name.as_str(), suffix)
}

/// Loosely based on `def_to_moniker`
///
/// Only returns a Symbol when it's a non-local symbol.
///     So if the visibility isn't outside of a document, then it will return None
fn moniker_to_symbol(moniker: &MonikerResult) -> scip_types::Symbol {
    use scip_types::descriptor::Suffix::*;

    let package_name = moniker.package_information.name.clone();
    let version = moniker.package_information.version.clone();
    let descriptors = moniker
        .identifier
        .description
        .iter()
        .map(|desc| {
            new_descriptor(
                desc.name.clone(),
                match desc.desc {
                    MonikerDescriptorKind::Namespace => Namespace,
                    MonikerDescriptorKind::Type => Type,
                    MonikerDescriptorKind::Term => Term,
                    MonikerDescriptorKind::Method => Method,
                    MonikerDescriptorKind::TypeParameter => TypeParameter,
                    MonikerDescriptorKind::Parameter => Parameter,
                    MonikerDescriptorKind::Macro => Macro,
                    MonikerDescriptorKind::Meta => Meta,
                },
            )
        })
        .collect();

    scip_types::Symbol {
        scheme: "rust-analyzer".into(),
        package: Some(scip_types::Package {
            manager: "cargo".to_string(),
            name: package_name,
            version,
            ..Default::default()
        })
        .into(),
        descriptors,
        ..Default::default()
    }
}

#[cfg(test)]
mod test {
    use super::*;
    use hir::Semantics;
    use ide::{AnalysisHost, FilePosition};
    use ide_db::defs::IdentClass;
    use ide_db::{base_db::fixture::ChangeFixture, helpers::pick_best_token};
    use scip::symbol::format_symbol;
    use syntax::SyntaxKind::*;
    use syntax::{AstNode, T};

    fn position(ra_fixture: &str) -> (AnalysisHost, FilePosition) {
        let mut host = AnalysisHost::default();
        let change_fixture = ChangeFixture::parse(ra_fixture);
        host.raw_database_mut().apply_change(change_fixture.change);
        let (file_id, range_or_offset) =
            change_fixture.file_position.expect("expected a marker ($0)");
        let offset = range_or_offset.expect_offset();
        (host, FilePosition { file_id, offset })
    }

    /// If expected == "", then assert that there are no symbols (this is basically local symbol)
    #[track_caller]
    fn check_symbol(ra_fixture: &str, expected: &str) {
        let (host, position) = position(ra_fixture);

        let FilePosition { file_id, offset } = position;

        let db = host.raw_database();
        let sema = &Semantics::new(db);
        let file = sema.parse(file_id).syntax().clone();
        let original_token = pick_best_token(file.token_at_offset(offset), |kind| match kind {
            IDENT
            | INT_NUMBER
            | LIFETIME_IDENT
            | T![self]
            | T![super]
            | T![crate]
            | T![Self]
            | COMMENT => 2,
            kind if kind.is_trivia() => 0,
            _ => 1,
        })
        .expect("OK OK");

        let navs = sema
            .descend_into_macros(original_token.clone())
            .into_iter()
            .filter_map(|token| {
                IdentClass::classify_token(sema, &token).map(IdentClass::definitions).map(|it| {
                    it.into_iter().flat_map(|def| {
                        let module = def.module(db).unwrap();
                        let current_crate = module.krate();

                        match MonikerResult::from_def(sema.db, def, current_crate) {
                            Some(moniker_result) => Some(moniker_to_symbol(&moniker_result)),
                            None => None,
                        }
                    })
                })
            })
            .flatten()
            .collect::<Vec<_>>();

        if expected == "" {
            assert_eq!(0, navs.len(), "must have no symbols {:?}", navs);
            return;
        }

        assert_eq!(1, navs.len(), "must have one symbol {:?}", navs);

        let res = navs.get(0).unwrap();
        let formatted = format_symbol(res.clone());
        assert_eq!(formatted, expected);
    }

    #[test]
    fn basic() {
        check_symbol(
            r#"
//- /lib.rs crate:main deps:foo
use foo::example_mod::func;
fn main() {
    func$0();
}
//- /foo/lib.rs crate:foo@CratesIo:0.1.0,https://a.b/foo.git
pub mod example_mod {
    pub fn func() {}
}
"#,
            "rust-analyzer cargo foo 0.1.0 example_mod/func().",
        );
    }

    #[test]
    fn symbol_for_trait() {
        check_symbol(
            r#"
//- /foo/lib.rs crate:foo@CratesIo:0.1.0,https://a.b/foo.git
pub mod module {
    pub trait MyTrait {
        pub fn func$0() {}
    }
}
"#,
            "rust-analyzer cargo foo 0.1.0 module/MyTrait#func().",
        );
    }

    #[test]
    fn symbol_for_trait_constant() {
        check_symbol(
            r#"
    //- /foo/lib.rs crate:foo@CratesIo:0.1.0,https://a.b/foo.git
    pub mod module {
        pub trait MyTrait {
            const MY_CONST$0: u8;
        }
    }
    "#,
            "rust-analyzer cargo foo 0.1.0 module/MyTrait#MY_CONST.",
        );
    }

    #[test]
    fn symbol_for_trait_type() {
        check_symbol(
            r#"
    //- /foo/lib.rs crate:foo@CratesIo:0.1.0,https://a.b/foo.git
    pub mod module {
        pub trait MyTrait {
            type MyType$0;
        }
    }
    "#,
            // "foo::module::MyTrait::MyType",
            "rust-analyzer cargo foo 0.1.0 module/MyTrait#[MyType]",
        );
    }

    #[test]
    fn symbol_for_trait_impl_function() {
        check_symbol(
            r#"
    //- /foo/lib.rs crate:foo@CratesIo:0.1.0,https://a.b/foo.git
    pub mod module {
        pub trait MyTrait {
            pub fn func() {}
        }

        struct MyStruct {}

        impl MyTrait for MyStruct {
            pub fn func$0() {}
        }
    }
    "#,
            // "foo::module::MyStruct::MyTrait::func",
            "rust-analyzer cargo foo 0.1.0 module/MyStruct#MyTrait#func().",
        );
    }

    #[test]
    fn symbol_for_field() {
        check_symbol(
            r#"
    //- /lib.rs crate:main deps:foo
    use foo::St;
    fn main() {
        let x = St { a$0: 2 };
    }
    //- /foo/lib.rs crate:foo@CratesIo:0.1.0,https://a.b/foo.git
    pub struct St {
        pub a: i32,
    }
    "#,
            "rust-analyzer cargo foo 0.1.0 St#a.",
        );
    }

    #[test]
    fn local_symbol_for_local() {
        check_symbol(
            r#"
    //- /lib.rs crate:main deps:foo
    use foo::module::func;
    fn main() {
        func();
    }
    //- /foo/lib.rs crate:foo@CratesIo:0.1.0,https://a.b/foo.git
    pub mod module {
        pub fn func() {
            let x$0 = 2;
        }
    }
    "#,
            "",
        );
    }
}