//! Handles build script specific information

use std::{
    io::BufReader,
    path::PathBuf,
    process::{Command, Stdio},
    sync::Arc,
};

use anyhow::Result;
use cargo_metadata::camino::Utf8Path;
use cargo_metadata::{BuildScript, Message};
use itertools::Itertools;
use paths::{AbsPath, AbsPathBuf};
use rustc_hash::FxHashMap;
use stdx::JodChild;

use crate::{cfg_flag::CfgFlag, CargoConfig};

#[derive(Debug, Clone, Default, PartialEq, Eq)]
pub(crate) struct BuildData {
    /// List of config flags defined by this package's build script
    pub(crate) cfgs: Vec<CfgFlag>,
    /// List of cargo-related environment variables with their value
    ///
    /// If the package has a build script which defines environment variables,
    /// they can also be found here.
    pub(crate) envs: Vec<(String, String)>,
    /// Directory where a build script might place its output
    pub(crate) out_dir: Option<AbsPathBuf>,
    /// Path to the proc-macro library file if this package exposes proc-macros
    pub(crate) proc_macro_dylib_path: Option<AbsPathBuf>,
}

#[derive(Clone, Debug)]
pub(crate) struct BuildDataConfig {
    cargo_toml: AbsPathBuf,
    cargo_features: CargoConfig,
    packages: Arc<Vec<cargo_metadata::Package>>,
}

impl PartialEq for BuildDataConfig {
    fn eq(&self, other: &Self) -> bool {
        Arc::ptr_eq(&self.packages, &other.packages)
    }
}

impl Eq for BuildDataConfig {}

#[derive(Debug, Default)]
pub struct BuildDataCollector {
    configs: FxHashMap<AbsPathBuf, BuildDataConfig>,
}

#[derive(Debug, Default, PartialEq, Eq)]
pub struct BuildDataResult {
    data: FxHashMap<AbsPathBuf, BuildDataMap>,
}

pub(crate) type BuildDataMap = FxHashMap<String, BuildData>;

impl BuildDataCollector {
    pub(crate) fn add_config(&mut self, workspace_root: &AbsPath, config: BuildDataConfig) {
        self.configs.insert(workspace_root.to_path_buf(), config);
    }

    pub fn collect(&mut self, progress: &dyn Fn(String)) -> Result<BuildDataResult> {
        let mut res = BuildDataResult::default();
        for (path, config) in self.configs.iter() {
            res.data.insert(
                path.clone(),
                collect_from_workspace(
                    &config.cargo_toml,
                    &config.cargo_features,
                    &config.packages,
                    progress,
                )?,
            );
        }
        Ok(res)
    }
}

impl BuildDataResult {
    pub(crate) fn get(&self, root: &AbsPath) -> Option<&BuildDataMap> {
        self.data.get(&root.to_path_buf())
    }
}

impl BuildDataConfig {
    pub(crate) fn new(
        cargo_toml: AbsPathBuf,
        cargo_features: CargoConfig,
        packages: Arc<Vec<cargo_metadata::Package>>,
    ) -> Self {
        Self { cargo_toml, cargo_features, packages }
    }
}

fn collect_from_workspace(
    cargo_toml: &AbsPath,
    cargo_features: &CargoConfig,
    packages: &Vec<cargo_metadata::Package>,
    progress: &dyn Fn(String),
) -> Result<BuildDataMap> {
    let mut cmd = Command::new(toolchain::cargo());
    cmd.args(&["check", "--workspace", "--message-format=json", "--manifest-path"])
        .arg(cargo_toml.as_ref());

    // --all-targets includes tests, benches and examples in addition to the
    // default lib and bins. This is an independent concept from the --targets
    // flag below.
    cmd.arg("--all-targets");

    if let Some(target) = &cargo_features.target {
        cmd.args(&["--target", target]);
    }

    if cargo_features.all_features {
        cmd.arg("--all-features");
    } else {
        if cargo_features.no_default_features {
            // FIXME: `NoDefaultFeatures` is mutual exclusive with `SomeFeatures`
            // https://github.com/oli-obk/cargo_metadata/issues/79
            cmd.arg("--no-default-features");
        }
        if !cargo_features.features.is_empty() {
            cmd.arg("--features");
            cmd.arg(cargo_features.features.join(" "));
        }
    }

    cmd.stdout(Stdio::piped()).stderr(Stdio::null()).stdin(Stdio::null());

    let mut child = cmd.spawn().map(JodChild)?;
    let child_stdout = child.stdout.take().unwrap();
    let stdout = BufReader::new(child_stdout);

    let mut res = BuildDataMap::default();
    for message in cargo_metadata::Message::parse_stream(stdout).flatten() {
        match message {
            Message::BuildScriptExecuted(BuildScript {
                package_id, out_dir, cfgs, env, ..
            }) => {
                let cfgs = {
                    let mut acc = Vec::new();
                    for cfg in cfgs {
                        match cfg.parse::<CfgFlag>() {
                            Ok(it) => acc.push(it),
                            Err(err) => {
                                anyhow::bail!("invalid cfg from cargo-metadata: {}", err)
                            }
                        };
                    }
                    acc
                };
                let res = res.entry(package_id.repr.clone()).or_default();
                // cargo_metadata crate returns default (empty) path for
                // older cargos, which is not absolute, so work around that.
                if !out_dir.as_str().is_empty() {
                    let out_dir = AbsPathBuf::assert(PathBuf::from(out_dir.into_os_string()));
                    res.out_dir = Some(out_dir);
                    res.cfgs = cfgs;
                }

                res.envs = env;
            }
            Message::CompilerArtifact(message) => {
                progress(format!("metadata {}", message.target.name));

                if message.target.kind.contains(&"proc-macro".to_string()) {
                    let package_id = message.package_id;
                    // Skip rmeta file
                    if let Some(filename) = message.filenames.iter().find(|name| is_dylib(name)) {
                        let filename = AbsPathBuf::assert(PathBuf::from(&filename));
                        let res = res.entry(package_id.repr.clone()).or_default();
                        res.proc_macro_dylib_path = Some(filename);
                    }
                }
            }
            Message::CompilerMessage(message) => {
                progress(message.target.name.clone());
            }
            Message::BuildFinished(_) => {}
            Message::TextLine(_) => {}
            _ => {}
        }
    }

    for package in packages {
        let build_data = res.entry(package.id.repr.clone()).or_default();
        inject_cargo_env(package, build_data);
        if let Some(out_dir) = &build_data.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()) {
                build_data.envs.push(("OUT_DIR".to_string(), out_dir));
            }
        }
    }

    Ok(res)
}

// FIXME: File a better way to know if it is a dylib
fn is_dylib(path: &Utf8Path) -> bool {
    match path.extension().map(|e| e.to_string().to_lowercase()) {
        None => false,
        Some(ext) => matches!(ext.as_str(), "dll" | "dylib" | "so"),
    }
}

/// Recreates the compile-time environment variables that Cargo sets.
///
/// Should be synced with <https://doc.rust-lang.org/cargo/reference/environment-variables.html#environment-variables-cargo-sets-for-crates>
fn inject_cargo_env(package: &cargo_metadata::Package, build_data: &mut BuildData) {
    let env = &mut build_data.envs;

    // FIXME: Missing variables:
    // CARGO_PKG_HOMEPAGE, CARGO_CRATE_NAME, CARGO_BIN_NAME, CARGO_BIN_EXE_<name>

    let mut manifest_dir = package.manifest_path.clone();
    manifest_dir.pop();
    env.push(("CARGO_MANIFEST_DIR".into(), manifest_dir.into_string()));

    // Not always right, but works for common cases.
    env.push(("CARGO".into(), "cargo".into()));

    env.push(("CARGO_PKG_VERSION".into(), package.version.to_string()));
    env.push(("CARGO_PKG_VERSION_MAJOR".into(), package.version.major.to_string()));
    env.push(("CARGO_PKG_VERSION_MINOR".into(), package.version.minor.to_string()));
    env.push(("CARGO_PKG_VERSION_PATCH".into(), package.version.patch.to_string()));

    let pre = package.version.pre.iter().map(|id| id.to_string()).format(".");
    env.push(("CARGO_PKG_VERSION_PRE".into(), pre.to_string()));

    let authors = package.authors.join(";");
    env.push(("CARGO_PKG_AUTHORS".into(), authors));

    env.push(("CARGO_PKG_NAME".into(), package.name.clone()));
    env.push(("CARGO_PKG_DESCRIPTION".into(), package.description.clone().unwrap_or_default()));
    //env.push(("CARGO_PKG_HOMEPAGE".into(), package.homepage.clone().unwrap_or_default()));
    env.push(("CARGO_PKG_REPOSITORY".into(), package.repository.clone().unwrap_or_default()));
    env.push(("CARGO_PKG_LICENSE".into(), package.license.clone().unwrap_or_default()));

    let license_file = package.license_file.as_ref().map(|buf| buf.to_string()).unwrap_or_default();
    env.push(("CARGO_PKG_LICENSE_FILE".into(), license_file));
}
