//! Handles lowering of build-system specific workspace information (`cargo
//! metadata` or `rust-project.json`) into representation stored in the salsa
//! database -- `CrateGraph`.

use std::{collections::VecDeque, fmt, fs, path::Path, process::Command};

use anyhow::{Context, Result};
use base_db::{CrateDisplayName, CrateGraph, CrateId, CrateName, Edition, Env, FileId, ProcMacro};
use cargo_workspace::DepKind;
use cfg::CfgOptions;
use paths::{AbsPath, AbsPathBuf};
use proc_macro_api::ProcMacroClient;
use rustc_hash::{FxHashMap, FxHashSet};

use crate::{
    build_data::{BuildDataResult, PackageBuildData, WorkspaceBuildData},
    cargo_workspace,
    cfg_flag::CfgFlag,
    rustc_cfg,
    sysroot::SysrootCrate,
    utf8_stdout, BuildDataCollector, CargoConfig, CargoWorkspace, ProjectJson, ProjectManifest,
    Sysroot, TargetKind,
};

/// `PackageRoot` describes a package root folder.
/// Which may be an external dependency, or a member of
/// the current workspace.
#[derive(Debug, Clone, Eq, PartialEq, Hash)]
pub struct PackageRoot {
    /// Is a member of the current workspace
    pub is_member: bool,
    pub include: Vec<AbsPathBuf>,
    pub exclude: Vec<AbsPathBuf>,
}

#[derive(Clone, Eq, PartialEq)]
pub enum ProjectWorkspace {
    /// Project workspace was discovered by running `cargo metadata` and `rustc --print sysroot`.
    Cargo {
        cargo: CargoWorkspace,
        sysroot: Sysroot,
        rustc: Option<CargoWorkspace>,
        /// Holds cfg flags for the current target. We get those by running
        /// `rustc --print cfg`.
        ///
        /// FIXME: make this a per-crate map, as, eg, build.rs might have a
        /// different target.
        rustc_cfg: Vec<CfgFlag>,
    },
    /// Project workspace was manually specified using a `rust-project.json` file.
    Json { project: ProjectJson, sysroot: Option<Sysroot>, rustc_cfg: Vec<CfgFlag> },
}

impl fmt::Debug for ProjectWorkspace {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        // Make sure this isn't too verbose.
        match self {
            ProjectWorkspace::Cargo { cargo, sysroot, rustc, rustc_cfg } => f
                .debug_struct("Cargo")
                .field("root", &cargo.workspace_root().file_name())
                .field("n_packages", &cargo.packages().len())
                .field("n_sysroot_crates", &sysroot.crates().len())
                .field(
                    "n_rustc_compiler_crates",
                    &rustc.as_ref().map_or(0, |rc| rc.packages().len()),
                )
                .field("n_rustc_cfg", &rustc_cfg.len())
                .finish(),
            ProjectWorkspace::Json { project, sysroot, rustc_cfg } => {
                let mut debug_struct = f.debug_struct("Json");
                debug_struct.field("n_crates", &project.n_crates());
                if let Some(sysroot) = sysroot {
                    debug_struct.field("n_sysroot_crates", &sysroot.crates().len());
                }
                debug_struct.field("n_rustc_cfg", &rustc_cfg.len());
                debug_struct.finish()
            }
        }
    }
}

impl ProjectWorkspace {
    pub fn load(
        manifest: ProjectManifest,
        config: &CargoConfig,
        progress: &dyn Fn(String),
    ) -> Result<ProjectWorkspace> {
        let res = match manifest {
            ProjectManifest::ProjectJson(project_json) => {
                let file = fs::read_to_string(&project_json).with_context(|| {
                    format!("Failed to read json file {}", project_json.display())
                })?;
                let data = serde_json::from_str(&file).with_context(|| {
                    format!("Failed to deserialize json file {}", project_json.display())
                })?;
                let project_location = project_json.parent().unwrap().to_path_buf();
                let project_json = ProjectJson::new(&project_location, data);
                ProjectWorkspace::load_inline(project_json, config.target.as_deref())?
            }
            ProjectManifest::CargoToml(cargo_toml) => {
                let cargo_version = utf8_stdout({
                    let mut cmd = Command::new(toolchain::cargo());
                    cmd.arg("--version");
                    cmd
                })?;

                let cargo = CargoWorkspace::from_cargo_metadata(&cargo_toml, config, progress)
                    .with_context(|| {
                        format!(
                            "Failed to read Cargo metadata from Cargo.toml file {}, {}",
                            cargo_toml.display(),
                            cargo_version
                        )
                    })?;

                let sysroot = if config.no_sysroot {
                    Sysroot::default()
                } else {
                    Sysroot::discover(&cargo_toml).with_context(|| {
                        format!(
                            "Failed to find sysroot for Cargo.toml file {}. Is rust-src installed?",
                            cargo_toml.display()
                        )
                    })?
                };

                let rustc_dir = if let Some(rustc_source) = &config.rustc_source {
                    use cargo_workspace::RustcSource;
                    match rustc_source {
                        RustcSource::Path(path) => Some(path.clone()),
                        RustcSource::Discover => Sysroot::discover_rustc(&cargo_toml),
                    }
                } else {
                    None
                };

                let rustc = if let Some(rustc_dir) = rustc_dir {
                    Some(
                        CargoWorkspace::from_cargo_metadata(&rustc_dir, config, progress)
                            .with_context(|| {
                                format!("Failed to read Cargo metadata for Rust sources")
                            })?,
                    )
                } else {
                    None
                };

                let rustc_cfg = rustc_cfg::get(Some(&cargo_toml), config.target.as_deref());
                ProjectWorkspace::Cargo { cargo, sysroot, rustc, rustc_cfg }
            }
            ProjectManifest::DetachedFile(_) => {
                todo!("TODO kb")
            }
        };

        Ok(res)
    }

    pub fn load_inline(
        project_json: ProjectJson,
        target: Option<&str>,
    ) -> Result<ProjectWorkspace> {
        let sysroot = match &project_json.sysroot_src {
            Some(path) => Some(Sysroot::load(path)?),
            None => None,
        };
        let rustc_cfg = rustc_cfg::get(None, target);
        Ok(ProjectWorkspace::Json { project: project_json, sysroot, rustc_cfg })
    }

    /// Returns the roots for the current `ProjectWorkspace`
    /// The return type contains the path and whether or not
    /// the root is a member of the current workspace
    pub fn to_roots(&self, build_data: Option<&BuildDataResult>) -> Vec<PackageRoot> {
        match self {
            ProjectWorkspace::Json { project, sysroot, rustc_cfg: _ } => project
                .crates()
                .map(|(_, krate)| PackageRoot {
                    is_member: krate.is_workspace_member,
                    include: krate.include.clone(),
                    exclude: krate.exclude.clone(),
                })
                .collect::<FxHashSet<_>>()
                .into_iter()
                .chain(sysroot.as_ref().into_iter().flat_map(|sysroot| {
                    sysroot.crates().map(move |krate| PackageRoot {
                        is_member: false,
                        include: vec![sysroot[krate].root_dir().to_path_buf()],
                        exclude: Vec::new(),
                    })
                }))
                .collect::<Vec<_>>(),
            ProjectWorkspace::Cargo { cargo, sysroot, rustc, rustc_cfg: _ } => cargo
                .packages()
                .map(|pkg| {
                    let is_member = cargo[pkg].is_member;
                    let pkg_root = cargo[pkg].root().to_path_buf();

                    let mut include = vec![pkg_root.clone()];
                    include.extend(
                        build_data
                            .and_then(|it| it.get(cargo.workspace_root()))
                            .and_then(|map| map.get(&cargo[pkg].id))
                            .and_then(|it| it.out_dir.clone()),
                    );

                    let mut exclude = vec![pkg_root.join(".git")];
                    if is_member {
                        exclude.push(pkg_root.join("target"));
                    } else {
                        exclude.push(pkg_root.join("tests"));
                        exclude.push(pkg_root.join("examples"));
                        exclude.push(pkg_root.join("benches"));
                    }
                    PackageRoot { is_member, include, exclude }
                })
                .chain(sysroot.crates().map(|krate| PackageRoot {
                    is_member: false,
                    include: vec![sysroot[krate].root_dir().to_path_buf()],
                    exclude: Vec::new(),
                }))
                .chain(rustc.into_iter().flat_map(|rustc| {
                    rustc.packages().map(move |krate| PackageRoot {
                        is_member: false,
                        include: vec![rustc[krate].root().to_path_buf()],
                        exclude: Vec::new(),
                    })
                }))
                .collect(),
        }
    }

    pub fn n_packages(&self) -> usize {
        match self {
            ProjectWorkspace::Json { project, .. } => project.n_crates(),
            ProjectWorkspace::Cargo { cargo, sysroot, rustc, .. } => {
                let rustc_package_len = rustc.as_ref().map_or(0, |rc| rc.packages().len());
                cargo.packages().len() + sysroot.crates().len() + rustc_package_len
            }
        }
    }

    pub fn to_crate_graph(
        &self,
        build_data: Option<&BuildDataResult>,
        proc_macro_client: Option<&ProcMacroClient>,
        load: &mut dyn FnMut(&AbsPath) -> Option<FileId>,
    ) -> CrateGraph {
        let _p = profile::span("ProjectWorkspace::to_crate_graph");
        let proc_macro_loader = |path: &Path| match proc_macro_client {
            Some(client) => client.by_dylib_path(path),
            None => Vec::new(),
        };

        let mut crate_graph = match self {
            ProjectWorkspace::Json { project, sysroot, rustc_cfg } => project_json_to_crate_graph(
                rustc_cfg.clone(),
                &proc_macro_loader,
                load,
                project,
                sysroot,
            ),
            ProjectWorkspace::Cargo { cargo, sysroot, rustc, rustc_cfg } => cargo_to_crate_graph(
                rustc_cfg.clone(),
                &proc_macro_loader,
                load,
                cargo,
                build_data.and_then(|it| it.get(cargo.workspace_root())),
                sysroot,
                rustc,
                rustc.as_ref().zip(build_data).and_then(|(it, map)| map.get(it.workspace_root())),
            ),
        };
        if crate_graph.patch_cfg_if() {
            log::debug!("Patched std to depend on cfg-if")
        } else {
            log::debug!("Did not patch std to depend on cfg-if")
        }
        crate_graph
    }

    pub fn collect_build_data_configs(&self, collector: &mut BuildDataCollector) {
        match self {
            ProjectWorkspace::Cargo { cargo, .. } => {
                collector.add_config(&cargo.workspace_root(), cargo.build_data_config().clone());
            }
            _ => {}
        }
    }
}

fn project_json_to_crate_graph(
    rustc_cfg: Vec<CfgFlag>,
    proc_macro_loader: &dyn Fn(&Path) -> Vec<ProcMacro>,
    load: &mut dyn FnMut(&AbsPath) -> Option<FileId>,
    project: &ProjectJson,
    sysroot: &Option<Sysroot>,
) -> CrateGraph {
    let mut crate_graph = CrateGraph::default();
    let sysroot_deps = sysroot
        .as_ref()
        .map(|sysroot| sysroot_to_crate_graph(&mut crate_graph, sysroot, rustc_cfg.clone(), load));

    let mut cfg_cache: FxHashMap<&str, Vec<CfgFlag>> = FxHashMap::default();
    let crates: FxHashMap<CrateId, CrateId> = project
        .crates()
        .filter_map(|(crate_id, krate)| {
            let file_path = &krate.root_module;
            let file_id = load(&file_path)?;
            Some((crate_id, krate, file_id))
        })
        .map(|(crate_id, krate, file_id)| {
            let env = krate.env.clone().into_iter().collect();
            let proc_macro = krate.proc_macro_dylib_path.clone().map(|it| proc_macro_loader(&it));

            let target_cfgs = match krate.target.as_deref() {
                Some(target) => {
                    cfg_cache.entry(target).or_insert_with(|| rustc_cfg::get(None, Some(target)))
                }
                None => &rustc_cfg,
            };

            let mut cfg_options = CfgOptions::default();
            cfg_options.extend(target_cfgs.iter().chain(krate.cfg.iter()).cloned());
            (
                crate_id,
                crate_graph.add_crate_root(
                    file_id,
                    krate.edition,
                    krate.display_name.clone(),
                    cfg_options,
                    env,
                    proc_macro.unwrap_or_default(),
                ),
            )
        })
        .collect();

    for (from, krate) in project.crates() {
        if let Some(&from) = crates.get(&from) {
            if let Some((public_deps, _proc_macro)) = &sysroot_deps {
                for (name, to) in public_deps.iter() {
                    add_dep(&mut crate_graph, from, name.clone(), *to)
                }
            }

            for dep in &krate.deps {
                if let Some(&to) = crates.get(&dep.crate_id) {
                    add_dep(&mut crate_graph, from, dep.name.clone(), to)
                }
            }
        }
    }
    crate_graph
}

fn cargo_to_crate_graph(
    rustc_cfg: Vec<CfgFlag>,
    proc_macro_loader: &dyn Fn(&Path) -> Vec<ProcMacro>,
    load: &mut dyn FnMut(&AbsPath) -> Option<FileId>,
    cargo: &CargoWorkspace,
    build_data_map: Option<&WorkspaceBuildData>,
    sysroot: &Sysroot,
    rustc: &Option<CargoWorkspace>,
    rustc_build_data_map: Option<&WorkspaceBuildData>,
) -> CrateGraph {
    let _p = profile::span("cargo_to_crate_graph");
    let mut crate_graph = CrateGraph::default();
    let (public_deps, libproc_macro) =
        sysroot_to_crate_graph(&mut crate_graph, sysroot, rustc_cfg.clone(), load);

    let mut cfg_options = CfgOptions::default();
    cfg_options.extend(rustc_cfg);

    let mut pkg_to_lib_crate = FxHashMap::default();

    // Add test cfg for non-sysroot crates
    cfg_options.insert_atom("test".into());
    cfg_options.insert_atom("debug_assertions".into());

    let mut pkg_crates = FxHashMap::default();
    // Does any crate signal to rust-analyzer that they need the rustc_private crates?
    let mut has_private = false;
    // Next, create crates for each package, target pair
    for pkg in cargo.packages() {
        has_private |= cargo[pkg].metadata.rustc_private;
        let mut lib_tgt = None;
        for &tgt in cargo[pkg].targets.iter() {
            if let Some(file_id) = load(&cargo[tgt].root) {
                let crate_id = add_target_crate_root(
                    &mut crate_graph,
                    &cargo[pkg],
                    build_data_map.and_then(|it| it.get(&cargo[pkg].id)),
                    &cfg_options,
                    proc_macro_loader,
                    file_id,
                    &cargo[tgt].name,
                );
                if cargo[tgt].kind == TargetKind::Lib {
                    lib_tgt = Some((crate_id, cargo[tgt].name.clone()));
                    pkg_to_lib_crate.insert(pkg, crate_id);
                }
                if cargo[tgt].is_proc_macro {
                    if let Some(proc_macro) = libproc_macro {
                        add_dep(
                            &mut crate_graph,
                            crate_id,
                            CrateName::new("proc_macro").unwrap(),
                            proc_macro,
                        );
                    }
                }

                pkg_crates.entry(pkg).or_insert_with(Vec::new).push((crate_id, cargo[tgt].kind));
            }
        }

        // Set deps to the core, std and to the lib target of the current package
        for (from, kind) in pkg_crates.get(&pkg).into_iter().flatten() {
            if let Some((to, name)) = lib_tgt.clone() {
                if to != *from && *kind != TargetKind::BuildScript {
                    // (build script can not depend on its library target)

                    // For root projects with dashes in their name,
                    // cargo metadata does not do any normalization,
                    // so we do it ourselves currently
                    let name = CrateName::normalize_dashes(&name);
                    add_dep(&mut crate_graph, *from, name, to);
                }
            }
            for (name, krate) in public_deps.iter() {
                add_dep(&mut crate_graph, *from, name.clone(), *krate);
            }
        }
    }

    // Now add a dep edge from all targets of upstream to the lib
    // target of downstream.
    for pkg in cargo.packages() {
        for dep in cargo[pkg].dependencies.iter() {
            let name = CrateName::new(&dep.name).unwrap();
            if let Some(&to) = pkg_to_lib_crate.get(&dep.pkg) {
                for (from, kind) in pkg_crates.get(&pkg).into_iter().flatten() {
                    if dep.kind == DepKind::Build && *kind != TargetKind::BuildScript {
                        // Only build scripts may depend on build dependencies.
                        continue;
                    }
                    if dep.kind != DepKind::Build && *kind == TargetKind::BuildScript {
                        // Build scripts may only depend on build dependencies.
                        continue;
                    }

                    add_dep(&mut crate_graph, *from, name.clone(), to)
                }
            }
        }
    }

    if has_private {
        // If the user provided a path to rustc sources, we add all the rustc_private crates
        // and create dependencies on them for the crates which opt-in to that
        if let Some(rustc_workspace) = rustc {
            handle_rustc_crates(
                rustc_workspace,
                load,
                &mut crate_graph,
                rustc_build_data_map,
                &cfg_options,
                proc_macro_loader,
                &mut pkg_to_lib_crate,
                &public_deps,
                cargo,
                &pkg_crates,
            );
        }
    }
    crate_graph
}

fn handle_rustc_crates(
    rustc_workspace: &CargoWorkspace,
    load: &mut dyn FnMut(&AbsPath) -> Option<FileId>,
    crate_graph: &mut CrateGraph,
    rustc_build_data_map: Option<&WorkspaceBuildData>,
    cfg_options: &CfgOptions,
    proc_macro_loader: &dyn Fn(&Path) -> Vec<ProcMacro>,
    pkg_to_lib_crate: &mut FxHashMap<la_arena::Idx<crate::PackageData>, CrateId>,
    public_deps: &[(CrateName, CrateId)],
    cargo: &CargoWorkspace,
    pkg_crates: &FxHashMap<la_arena::Idx<crate::PackageData>, Vec<(CrateId, TargetKind)>>,
) {
    let mut rustc_pkg_crates = FxHashMap::default();
    // The root package of the rustc-dev component is rustc_driver, so we match that
    let root_pkg =
        rustc_workspace.packages().find(|package| rustc_workspace[*package].name == "rustc_driver");
    // The rustc workspace might be incomplete (such as if rustc-dev is not
    // installed for the current toolchain) and `rustcSource` is set to discover.
    if let Some(root_pkg) = root_pkg {
        // Iterate through every crate in the dependency subtree of rustc_driver using BFS
        let mut queue = VecDeque::new();
        queue.push_back(root_pkg);
        while let Some(pkg) = queue.pop_front() {
            // Don't duplicate packages if they are dependended on a diamond pattern
            // N.B. if this line is ommitted, we try to analyse over 4_800_000 crates
            // which is not ideal
            if rustc_pkg_crates.contains_key(&pkg) {
                continue;
            }
            for dep in &rustc_workspace[pkg].dependencies {
                queue.push_back(dep.pkg);
            }
            for &tgt in rustc_workspace[pkg].targets.iter() {
                if rustc_workspace[tgt].kind != TargetKind::Lib {
                    continue;
                }
                if let Some(file_id) = load(&rustc_workspace[tgt].root) {
                    let crate_id = add_target_crate_root(
                        crate_graph,
                        &rustc_workspace[pkg],
                        rustc_build_data_map.and_then(|it| it.get(&rustc_workspace[pkg].id)),
                        &cfg_options,
                        proc_macro_loader,
                        file_id,
                        &rustc_workspace[tgt].name,
                    );
                    pkg_to_lib_crate.insert(pkg, crate_id);
                    // Add dependencies on core / std / alloc for this crate
                    for (name, krate) in public_deps.iter() {
                        add_dep(crate_graph, crate_id, name.clone(), *krate);
                    }
                    rustc_pkg_crates.entry(pkg).or_insert_with(Vec::new).push(crate_id);
                }
            }
        }
    }
    // Now add a dep edge from all targets of upstream to the lib
    // target of downstream.
    for pkg in rustc_pkg_crates.keys().copied() {
        for dep in rustc_workspace[pkg].dependencies.iter() {
            let name = CrateName::new(&dep.name).unwrap();
            if let Some(&to) = pkg_to_lib_crate.get(&dep.pkg) {
                for &from in rustc_pkg_crates.get(&pkg).into_iter().flatten() {
                    add_dep(crate_graph, from, name.clone(), to);
                }
            }
        }
    }
    // Add a dependency on the rustc_private crates for all targets of each package
    // which opts in
    for dep in rustc_workspace.packages() {
        let name = CrateName::normalize_dashes(&rustc_workspace[dep].name);

        if let Some(&to) = pkg_to_lib_crate.get(&dep) {
            for pkg in cargo.packages() {
                let package = &cargo[pkg];
                if !package.metadata.rustc_private {
                    continue;
                }
                for (from, _) in pkg_crates.get(&pkg).into_iter().flatten() {
                    // Avoid creating duplicate dependencies
                    // This avoids the situation where `from` depends on e.g. `arrayvec`, but
                    // `rust_analyzer` thinks that it should use the one from the `rustcSource`
                    // instead of the one from `crates.io`
                    if !crate_graph[*from].dependencies.iter().any(|d| d.name == name) {
                        add_dep(crate_graph, *from, name.clone(), to);
                    }
                }
            }
        }
    }
}

fn add_target_crate_root(
    crate_graph: &mut CrateGraph,
    pkg: &cargo_workspace::PackageData,
    build_data: Option<&PackageBuildData>,
    cfg_options: &CfgOptions,
    proc_macro_loader: &dyn Fn(&Path) -> Vec<ProcMacro>,
    file_id: FileId,
    cargo_name: &str,
) -> CrateId {
    let edition = pkg.edition;
    let cfg_options = {
        let mut opts = cfg_options.clone();
        for feature in pkg.active_features.iter() {
            opts.insert_key_value("feature".into(), feature.into());
        }
        if let Some(cfgs) = build_data.as_ref().map(|it| &it.cfgs) {
            opts.extend(cfgs.iter().cloned());
        }
        opts
    };

    let mut env = Env::default();
    if let Some(envs) = build_data.map(|it| &it.envs) {
        for (k, v) in envs {
            env.set(k, v.clone());
        }
    }

    let proc_macro = build_data
        .as_ref()
        .and_then(|it| it.proc_macro_dylib_path.as_ref())
        .map(|it| proc_macro_loader(&it))
        .unwrap_or_default();

    let display_name = CrateDisplayName::from_canonical_name(cargo_name.to_string());
    let crate_id = crate_graph.add_crate_root(
        file_id,
        edition,
        Some(display_name),
        cfg_options,
        env,
        proc_macro,
    );

    crate_id
}

fn sysroot_to_crate_graph(
    crate_graph: &mut CrateGraph,
    sysroot: &Sysroot,
    rustc_cfg: Vec<CfgFlag>,
    load: &mut dyn FnMut(&AbsPath) -> Option<FileId>,
) -> (Vec<(CrateName, CrateId)>, Option<CrateId>) {
    let _p = profile::span("sysroot_to_crate_graph");
    let mut cfg_options = CfgOptions::default();
    cfg_options.extend(rustc_cfg);
    let sysroot_crates: FxHashMap<SysrootCrate, CrateId> = sysroot
        .crates()
        .filter_map(|krate| {
            let file_id = load(&sysroot[krate].root)?;

            let env = Env::default();
            let proc_macro = vec![];
            let display_name = CrateDisplayName::from_canonical_name(sysroot[krate].name.clone());
            let crate_id = crate_graph.add_crate_root(
                file_id,
                Edition::Edition2018,
                Some(display_name),
                cfg_options.clone(),
                env,
                proc_macro,
            );
            Some((krate, crate_id))
        })
        .collect();

    for from in sysroot.crates() {
        for &to in sysroot[from].deps.iter() {
            let name = CrateName::new(&sysroot[to].name).unwrap();
            if let (Some(&from), Some(&to)) = (sysroot_crates.get(&from), sysroot_crates.get(&to)) {
                add_dep(crate_graph, from, name, to);
            }
        }
    }

    let public_deps = sysroot
        .public_deps()
        .map(|(name, idx)| (CrateName::new(name).unwrap(), sysroot_crates[&idx]))
        .collect::<Vec<_>>();

    let libproc_macro = sysroot.proc_macro().and_then(|it| sysroot_crates.get(&it).copied());
    (public_deps, libproc_macro)
}

fn add_dep(graph: &mut CrateGraph, from: CrateId, name: CrateName, to: CrateId) {
    if let Err(err) = graph.add_dep(from, name, to) {
        log::error!("{}", err)
    }
}