//! FIXME: write short doc here

mod cargo_workspace;
mod project_json;
mod sysroot;
mod cfg_flag;

use std::{
    fmt,
    fs::{self, read_dir, ReadDir},
    io,
    process::Command,
};

use anyhow::{bail, Context, Result};
use base_db::{CrateGraph, CrateId, CrateName, Edition, Env, FileId};
use cfg::CfgOptions;
use paths::{AbsPath, AbsPathBuf};
use rustc_hash::{FxHashMap, FxHashSet};

use crate::cfg_flag::CfgFlag;

pub use crate::{
    cargo_workspace::{CargoConfig, CargoWorkspace, Package, Target, TargetKind},
    project_json::{ProjectJson, ProjectJsonData},
    sysroot::Sysroot,
};

pub use proc_macro_api::ProcMacroClient;

#[derive(Clone, Eq, PartialEq)]
pub enum ProjectWorkspace {
    /// Project workspace was discovered by running `cargo metadata` and `rustc --print sysroot`.
    Cargo { cargo: CargoWorkspace, sysroot: Sysroot },
    /// Project workspace was manually specified using a `rust-project.json` file.
    Json { project: ProjectJson },
}

impl fmt::Debug for ProjectWorkspace {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self {
            ProjectWorkspace::Cargo { cargo, sysroot } => f
                .debug_struct("Cargo")
                .field("n_packages", &cargo.packages().len())
                .field("n_sysroot_crates", &sysroot.crates().len())
                .finish(),
            ProjectWorkspace::Json { project } => {
                let mut debug_struct = f.debug_struct("Json");
                debug_struct.field("n_crates", &project.n_crates());
                if let Some(sysroot) = &project.sysroot {
                    debug_struct.field("n_sysroot_crates", &sysroot.crates().len());
                }
                debug_struct.finish()
            }
        }
    }
}

/// `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(Debug, Clone, PartialEq, Eq, Hash, Ord, PartialOrd)]
pub enum ProjectManifest {
    ProjectJson(AbsPathBuf),
    CargoToml(AbsPathBuf),
}

impl ProjectManifest {
    pub fn from_manifest_file(path: AbsPathBuf) -> Result<ProjectManifest> {
        if path.ends_with("rust-project.json") {
            return Ok(ProjectManifest::ProjectJson(path));
        }
        if path.ends_with("Cargo.toml") {
            return Ok(ProjectManifest::CargoToml(path));
        }
        bail!("project root must point to Cargo.toml or rust-project.json: {}", path.display())
    }

    pub fn discover_single(path: &AbsPath) -> Result<ProjectManifest> {
        let mut candidates = ProjectManifest::discover(path)?;
        let res = match candidates.pop() {
            None => bail!("no projects"),
            Some(it) => it,
        };

        if !candidates.is_empty() {
            bail!("more than one project")
        }
        Ok(res)
    }

    pub fn discover(path: &AbsPath) -> io::Result<Vec<ProjectManifest>> {
        if let Some(project_json) = find_in_parent_dirs(path, "rust-project.json") {
            return Ok(vec![ProjectManifest::ProjectJson(project_json)]);
        }
        return find_cargo_toml(path)
            .map(|paths| paths.into_iter().map(ProjectManifest::CargoToml).collect());

        fn find_cargo_toml(path: &AbsPath) -> io::Result<Vec<AbsPathBuf>> {
            match find_in_parent_dirs(path, "Cargo.toml") {
                Some(it) => Ok(vec![it]),
                None => Ok(find_cargo_toml_in_child_dir(read_dir(path)?)),
            }
        }

        fn find_in_parent_dirs(path: &AbsPath, target_file_name: &str) -> Option<AbsPathBuf> {
            if path.ends_with(target_file_name) {
                return Some(path.to_path_buf());
            }

            let mut curr = Some(path);

            while let Some(path) = curr {
                let candidate = path.join(target_file_name);
                if candidate.exists() {
                    return Some(candidate);
                }
                curr = path.parent();
            }

            None
        }

        fn find_cargo_toml_in_child_dir(entities: ReadDir) -> Vec<AbsPathBuf> {
            // Only one level down to avoid cycles the easy way and stop a runaway scan with large projects
            entities
                .filter_map(Result::ok)
                .map(|it| it.path().join("Cargo.toml"))
                .filter(|it| it.exists())
                .map(AbsPathBuf::assert)
                .collect()
        }
    }

    pub fn discover_all(paths: &[impl AsRef<AbsPath>]) -> Vec<ProjectManifest> {
        let mut res = paths
            .iter()
            .filter_map(|it| ProjectManifest::discover(it.as_ref()).ok())
            .flatten()
            .collect::<FxHashSet<_>>()
            .into_iter()
            .collect::<Vec<_>>();
        res.sort();
        res
    }
}

impl ProjectWorkspace {
    pub fn load(
        manifest: ProjectManifest,
        cargo_config: &CargoConfig,
        with_sysroot: bool,
    ) -> 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 = ProjectJson::new(&project_location, data);
                ProjectWorkspace::Json { project }
            }
            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, cargo_config)
                    .with_context(|| {
                        format!(
                            "Failed to read Cargo metadata from Cargo.toml file {}, {}",
                            cargo_toml.display(),
                            cargo_version
                        )
                    })?;
                let sysroot = if with_sysroot {
                    Sysroot::discover(&cargo_toml).with_context(|| {
                        format!(
                            "Failed to find sysroot for Cargo.toml file {}. Is rust-src installed?",
                            cargo_toml.display()
                        )
                    })?
                } else {
                    Sysroot::default()
                };
                ProjectWorkspace::Cargo { cargo, sysroot }
            }
        };

        Ok(res)
    }

    /// 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) -> Vec<PackageRoot> {
        match self {
            ProjectWorkspace::Json { project } => project
                .crates()
                .map(|(_, krate)| PackageRoot {
                    is_member: krate.is_workspace_member,
                    include: krate.include.clone(),
                    exclude: krate.exclude.clone(),
                })
                .collect::<FxHashSet<_>>()
                .into_iter()
                .chain(project.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 } => 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(cargo[pkg].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(),
                }))
                .collect(),
        }
    }

    pub fn proc_macro_dylib_paths(&self) -> Vec<AbsPathBuf> {
        match self {
            ProjectWorkspace::Json { project } => project
                .crates()
                .filter_map(|(_, krate)| krate.proc_macro_dylib_path.as_ref())
                .cloned()
                .collect(),
            ProjectWorkspace::Cargo { cargo, sysroot: _sysroot } => cargo
                .packages()
                .filter_map(|pkg| cargo[pkg].proc_macro_dylib_path.as_ref())
                .cloned()
                .collect(),
        }
    }

    pub fn n_packages(&self) -> usize {
        match self {
            ProjectWorkspace::Json { project, .. } => project.n_crates(),
            ProjectWorkspace::Cargo { cargo, sysroot } => {
                cargo.packages().len() + sysroot.crates().len()
            }
        }
    }

    pub fn to_crate_graph(
        &self,
        target: Option<&str>,
        proc_macro_client: &ProcMacroClient,
        load: &mut dyn FnMut(&AbsPath) -> Option<FileId>,
    ) -> CrateGraph {
        let mut crate_graph = CrateGraph::default();
        match self {
            ProjectWorkspace::Json { project } => {
                let sysroot_dps = project
                    .sysroot
                    .as_ref()
                    .map(|sysroot| sysroot_to_crate_graph(&mut crate_graph, sysroot, target, load));

                let mut cfg_cache: FxHashMap<Option<&str>, Vec<CfgFlag>> = FxHashMap::default();
                let crates: FxHashMap<_, _> = project
                    .crates()
                    .filter_map(|(crate_id, krate)| {
                        let file_path = &krate.root_module;
                        let file_id = load(&file_path)?;

                        let env = krate.env.clone().into_iter().collect();
                        let proc_macro = krate
                            .proc_macro_dylib_path
                            .clone()
                            .map(|it| proc_macro_client.by_dylib_path(&it));

                        let target = krate.target.as_deref().or(target);
                        let target_cfgs = cfg_cache
                            .entry(target)
                            .or_insert_with(|| get_rustc_cfg_options(target));

                        let mut cfg_options = CfgOptions::default();
                        cfg_options.extend(target_cfgs.iter().chain(krate.cfg.iter()).cloned());

                        Some((
                            crate_id,
                            crate_graph.add_crate_root(
                                file_id,
                                krate.edition,
                                // FIXME json definitions can store the crate name
                                None,
                                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_dps {
                            for (name, to) in public_deps.iter() {
                                if let Err(_) = crate_graph.add_dep(from, name.clone(), *to) {
                                    log::error!("cyclic dependency on {} for {:?}", name, from)
                                }
                            }
                        }

                        for dep in &krate.deps {
                            let to_crate_id = dep.crate_id;
                            if let Some(&to) = crates.get(&to_crate_id) {
                                if let Err(_) = crate_graph.add_dep(from, dep.name.clone(), to) {
                                    log::error!("cyclic dependency {:?} -> {:?}", from, to);
                                }
                            }
                        }
                    }
                }
            }
            ProjectWorkspace::Cargo { cargo, sysroot } => {
                let (public_deps, libproc_macro) =
                    sysroot_to_crate_graph(&mut crate_graph, sysroot, target, load);

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

                let mut pkg_to_lib_crate = FxHashMap::default();
                let mut pkg_crates = FxHashMap::default();

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

                // Next, create crates for each package, target pair
                for pkg in cargo.packages() {
                    let mut lib_tgt = None;
                    for &tgt in cargo[pkg].targets.iter() {
                        let root = cargo[tgt].root.as_path();
                        if let Some(file_id) = load(root) {
                            let edition = cargo[pkg].edition;
                            let cfg_options = {
                                let mut opts = cfg_options.clone();
                                for feature in cargo[pkg].features.iter() {
                                    opts.insert_key_value("feature".into(), feature.into());
                                }
                                opts.extend(cargo[pkg].cfgs.iter().cloned());
                                opts
                            };
                            let mut env = Env::default();
                            if let Some(out_dir) = &cargo[pkg].out_dir {
                                // NOTE: cargo and rustc seem to hide non-UTF-8 strings from env! and option_env!()
                                if let Some(out_dir) = out_dir.to_str().map(|s| s.to_owned()) {
                                    env.set("OUT_DIR", out_dir);
                                }
                            }
                            let proc_macro = cargo[pkg]
                                .proc_macro_dylib_path
                                .as_ref()
                                .map(|it| proc_macro_client.by_dylib_path(&it))
                                .unwrap_or_default();

                            let crate_id = crate_graph.add_crate_root(
                                file_id,
                                edition,
                                Some(cargo[pkg].name.clone()),
                                cfg_options,
                                env,
                                proc_macro.clone(),
                            );
                            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 {
                                    if let Err(_) = crate_graph.add_dep(
                                        crate_id,
                                        CrateName::new("proc_macro").unwrap(),
                                        proc_macro,
                                    ) {
                                        log::error!(
                                            "cyclic dependency on proc_macro for {}",
                                            &cargo[pkg].name
                                        )
                                    }
                                }
                            }

                            pkg_crates.entry(pkg).or_insert_with(Vec::new).push(crate_id);
                        }
                    }

                    // Set deps to the core, std and to the lib target of the current package
                    for &from in pkg_crates.get(&pkg).into_iter().flatten() {
                        if let Some((to, name)) = lib_tgt.clone() {
                            // 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);
                            if to != from && crate_graph.add_dep(from, name, to).is_err() {
                                log::error!(
                                    "cyclic dependency between targets of {}",
                                    &cargo[pkg].name
                                )
                            }
                        }
                        for (name, krate) in public_deps.iter() {
                            if let Err(_) = crate_graph.add_dep(from, name.clone(), *krate) {
                                log::error!(
                                    "cyclic dependency on {} for {}",
                                    name,
                                    &cargo[pkg].name
                                )
                            }
                        }
                    }
                }

                // 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 in pkg_crates.get(&pkg).into_iter().flatten() {
                                if let Err(_) = crate_graph.add_dep(from, name.clone(), to) {
                                    log::error!(
                                        "cyclic dependency {} -> {}",
                                        &cargo[pkg].name,
                                        &cargo[dep.pkg].name
                                    )
                                }
                            }
                        }
                    }
                }
            }
        }
        crate_graph
    }
}

fn get_rustc_cfg_options(target: Option<&str>) -> Vec<CfgFlag> {
    let mut res = Vec::new();

    // Some nightly-only cfgs, which are required for stdlib
    res.push(CfgFlag::Atom("target_thread_local".into()));
    for &ty in ["8", "16", "32", "64", "cas", "ptr"].iter() {
        for &key in ["target_has_atomic", "target_has_atomic_load_store"].iter() {
            res.push(CfgFlag::KeyValue { key: key.to_string(), value: ty.into() });
        }
    }

    let rustc_cfgs = {
        let mut cmd = Command::new(toolchain::rustc());
        cmd.args(&["--print", "cfg", "-O"]);
        if let Some(target) = target {
            cmd.args(&["--target", target]);
        }
        utf8_stdout(cmd)
    };

    match rustc_cfgs {
        Ok(rustc_cfgs) => res.extend(rustc_cfgs.lines().map(|it| it.parse().unwrap())),
        Err(e) => log::error!("failed to get rustc cfgs: {:#}", e),
    }

    res
}

fn utf8_stdout(mut cmd: Command) -> Result<String> {
    let output = cmd.output().with_context(|| format!("{:?} failed", cmd))?;
    if !output.status.success() {
        match String::from_utf8(output.stderr) {
            Ok(stderr) if !stderr.is_empty() => {
                bail!("{:?} failed, {}\nstderr:\n{}", cmd, output.status, stderr)
            }
            _ => bail!("{:?} failed, {}", cmd, output.status),
        }
    }
    let stdout = String::from_utf8(output.stdout)?;
    Ok(stdout.trim().to_string())
}

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

            let env = Env::default();
            let proc_macro = vec![];
            let name = sysroot[krate].name.clone();
            let crate_id = crate_graph.add_crate_root(
                file_id,
                Edition::Edition2018,
                Some(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)) {
                if let Err(_) = crate_graph.add_dep(from, name, to) {
                    log::error!("cyclic dependency between sysroot crates")
                }
            }
        }
    }

    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)
}