use crate::core::compiler::{CompileKind, CompileMode, Layout, RustcTargetData};
use crate::core::profiles::Profiles;
use crate::core::{PackageIdSpec, PackageIdSpecQuery, TargetKind, Workspace};
use crate::ops;
use crate::util::HumanBytes;
use crate::util::edit_distance;
use crate::util::errors::CargoResult;
use crate::util::interning::InternedString;
use crate::util::{GlobalContext, Progress, ProgressStyle};
use anyhow::bail;
use cargo_util::paths;
use cargo_util_terminal::report::Level;
use indexmap::{IndexMap, IndexSet};

use std::ffi::OsString;
use std::io::Read;
use std::path::{Path, PathBuf};
use std::rc::Rc;
use std::{fs, io};

pub struct CleanOptions<'gctx> {
    pub gctx: &'gctx GlobalContext,
    /// A list of packages to clean. If empty, everything is cleaned.
    pub spec: IndexSet<String>,
    /// The target arch triple to clean, or None for the host arch
    pub targets: Vec<String>,
    /// Whether to clean the release directory
    pub profile_specified: bool,
    /// Whether to clean the directory of a certain build profile
    pub requested_profile: InternedString,
    /// Whether to just clean the doc directory
    pub doc: bool,
    /// If set, doesn't delete anything.
    pub dry_run: bool,
    /// true if target-dir was was explicitly specified via --target-dir
    pub explicit_target_dir_arg: bool,
}

pub struct CleanContext<'gctx> {
    pub gctx: &'gctx GlobalContext,
    progress: Box<dyn CleaningProgressBar + 'gctx>,
    pub dry_run: bool,
    num_files_removed: u64,
    num_dirs_removed: u64,
    total_bytes_removed: u64,
}

/// Cleans various caches.
pub fn clean(ws: &Workspace<'_>, opts: &CleanOptions<'_>) -> CargoResult<()> {
    let mut target_dir = ws.target_dir();
    let mut build_dir = ws.build_dir();
    let gctx = opts.gctx;
    let mut clean_ctx = CleanContext::new(gctx);
    clean_ctx.dry_run = opts.dry_run;

    const CLEAN_ABORT_NOTE: &str =
        "cleaning has been aborted to prevent accidental deletion of unrelated files";

    // make sure target_dir is a directory if it exists so that we don't delete files
    if let Ok(meta) = fs::symlink_metadata(target_dir.as_path_unlocked()) {
        // do not error if target_dir is symlink; let cargo delete it
        if !meta.is_symlink() && !meta.is_dir() {
            let title = format!("cannot clean `{}`: not a directory", target_dir.display());
            let report = [Level::ERROR
                .primary_title(title)
                .element(Level::NOTE.message(CLEAN_ABORT_NOTE))];
            gctx.shell().print_report(&report, false)?;
            return Err(crate::AlreadyPrintedError::new(anyhow::anyhow!("")).into());
        }
    }

    // do some validation on target_dir if it was specified via --target-dir
    if opts.explicit_target_dir_arg {
        let target_dir_path = target_dir.as_path_unlocked();

        // perform validation on target_dir only if it exists and check if the target directory has a valid CACHEDIR.TAG
        if target_dir_path.exists()
            && let Err(err) = validate_target_dir_tag(target_dir_path)
        {
            // if target_dir was passed explicitly via --target-dir, then hard error if validation fails
            let title = format!("cannot clean `{}`: {err}", target_dir_path.display());
            let report = [Level::ERROR
                .primary_title(title)
                .element(Level::NOTE.message(CLEAN_ABORT_NOTE))];
            gctx.shell().print_report(&report, false)?;
            return Err(crate::AlreadyPrintedError::new(anyhow::anyhow!("")).into());
        }
    }

    if opts.doc {
        if !opts.spec.is_empty() {
            // FIXME: https://github.com/rust-lang/cargo/issues/8790
            // This should support the ability to clean specific packages
            // within the doc directory. It's a little tricky since it
            // needs to find all documentable targets, but also consider
            // the fact that target names might overlap with dependency
            // names and such.
            bail!("--doc cannot be used with -p");
        }
        // If the doc option is set, we just want to delete the doc directory.
        target_dir = target_dir.join("doc");
        clean_ctx.remove_paths(&[target_dir.into_path_unlocked()])?;
    } else {
        let profiles = Profiles::new(&ws, opts.requested_profile)?;

        if opts.profile_specified {
            // After parsing profiles we know the dir-name of the profile, if a profile
            // was passed from the command line. If so, delete only the directory of
            // that profile.
            let dir_name = profiles.get_dir_name();
            target_dir = target_dir.join(dir_name);
            build_dir = build_dir.join(dir_name);
        }

        // If we have a spec, then we need to delete some packages, otherwise, just
        // remove the whole target directory and be done with it!
        //
        // Note that we don't bother grabbing a lock here as we're just going to
        // blow it all away anyway.
        if opts.spec.is_empty() {
            let paths: &[PathBuf] = if build_dir != target_dir {
                &[
                    target_dir.into_path_unlocked(),
                    build_dir.into_path_unlocked(),
                ]
            } else {
                &[target_dir.into_path_unlocked()]
            };
            clean_ctx.remove_paths(paths)?;
        } else {
            clean_specs(
                &mut clean_ctx,
                &ws,
                &profiles,
                &opts.targets,
                &opts.spec,
                opts.dry_run,
            )?;
        }
    }

    clean_ctx.display_summary()?;
    Ok(())
}

fn validate_target_dir_tag(target_dir_path: &Path) -> CargoResult<()> {
    const TAG_SIGNATURE: &[u8] = b"Signature: 8a477f597d28d172789f06886806bc55";

    let tag_path = target_dir_path.join("CACHEDIR.TAG");

    // per https://bford.info/cachedir the tag file must not be a symlink
    if tag_path.is_symlink() {
        bail!("expect `CACHEDIR.TAG` to be a regular file, got a symlink");
    }

    if !tag_path.is_file() {
        bail!("missing or invalid `CACHEDIR.TAG` file");
    }

    let mut file = fs::File::open(&tag_path)
        .map_err(|err| anyhow::anyhow!("failed to open `{}`: {}", tag_path.display(), err))?;

    let mut buf = [0u8; TAG_SIGNATURE.len()];
    match file.read_exact(&mut buf) {
        Ok(()) if &buf[..] == TAG_SIGNATURE => {}
        Err(e) if e.kind() != io::ErrorKind::UnexpectedEof => {
            bail!("failed to read `{}`: {e}", tag_path.display());
        }
        _ => {
            bail!("invalid signature in `CACHEDIR.TAG` file");
        }
    }

    Ok(())
}

fn clean_specs(
    clean_ctx: &mut CleanContext<'_>,
    ws: &Workspace<'_>,
    profiles: &Profiles,
    targets: &[String],
    spec: &IndexSet<String>,
    dry_run: bool,
) -> CargoResult<()> {
    // Clean specific packages.
    let requested_kinds = CompileKind::from_requested_targets(clean_ctx.gctx, targets)?;
    let target_data = RustcTargetData::new(ws, &requested_kinds)?;
    let (pkg_set, resolve) = ops::resolve_ws(ws, dry_run)?;
    let prof_dir_name = profiles.get_dir_name();
    let host_layout = Layout::new(ws, None, &prof_dir_name, true, true)?;
    // Convert requested kinds to a Vec of layouts.
    let target_layouts: Vec<(CompileKind, Layout)> = requested_kinds
        .into_iter()
        .filter_map(|kind| match kind {
            CompileKind::Target(target) => {
                match Layout::new(ws, Some(target), &prof_dir_name, true, true) {
                    Ok(layout) => Some(Ok((kind, layout))),
                    Err(e) => Some(Err(e)),
                }
            }
            CompileKind::Host => None,
        })
        .collect::<CargoResult<_>>()?;
    // A Vec of layouts. This is a little convoluted because there can only be
    // one host_layout.
    let layouts = if target_layouts.is_empty() {
        vec![(CompileKind::Host, &host_layout)]
    } else {
        target_layouts
            .iter()
            .map(|(kind, layout)| (*kind, layout))
            .collect()
    };
    // Create a Vec that also includes the host for things that need to clean both.
    let layouts_with_host: Vec<(CompileKind, &Layout)> =
        std::iter::once((CompileKind::Host, &host_layout))
            .chain(layouts.iter().map(|(k, l)| (*k, *l)))
            .collect();

    // Cleaning individual rustdoc crates is currently not supported.
    // For example, the search index would need to be rebuilt to fully
    // remove it (otherwise you're left with lots of broken links).
    // Doc tests produce no output.

    // Get Packages for the specified specs.
    let mut pkg_ids = Vec::new();
    for spec_str in spec.iter() {
        // Translate the spec to a Package.
        let spec = PackageIdSpec::parse(spec_str)?;
        if spec.partial_version().is_some() {
            clean_ctx.gctx.shell().warn(&format!(
                "version qualifier in `-p {}` is ignored, \
                cleaning all versions of `{}` found",
                spec_str,
                spec.name()
            ))?;
        }
        if spec.url().is_some() {
            clean_ctx.gctx.shell().warn(&format!(
                "url qualifier in `-p {}` ignored, \
                cleaning all versions of `{}` found",
                spec_str,
                spec.name()
            ))?;
        }
        let matches: Vec<_> = resolve.iter().filter(|id| spec.matches(*id)).collect();
        if matches.is_empty() {
            let mut suggestion = String::new();
            suggestion.push_str(&edit_distance::closest_msg(
                &spec.name(),
                resolve.iter(),
                |id| id.name().as_str(),
                "package",
            ));
            anyhow::bail!(
                "package ID specification `{}` did not match any packages{}",
                spec,
                suggestion
            );
        }
        pkg_ids.extend(matches);
    }
    let packages = pkg_set.get_many(pkg_ids)?;

    clean_ctx.progress = Box::new(CleaningPackagesBar::new(clean_ctx.gctx, packages.len()));
    let mut dirs_to_clean = DirectoriesToClean::default();

    if clean_ctx.gctx.cli_unstable().build_dir_new_layout {
        for pkg in packages {
            clean_ctx.progress.on_cleaning_package(&pkg.name())?;

            // Remove intermediate artifacts
            for (_compile_kind, layout) in &layouts_with_host {
                let dir = layout.build_dir().build_unit(&pkg.name());
                clean_ctx.rm_rf(&dir)?;
            }

            // Remove the uplifted copy.
            for target in pkg.targets() {
                if target.is_custom_build() {
                    continue;
                }
                let crate_name: Rc<str> = target.crate_name().into();
                for &mode in &[
                    CompileMode::Build,
                    CompileMode::Test,
                    CompileMode::Check { test: false },
                ] {
                    for (compile_kind, layout) in &layouts {
                        let triple = target_data.short_name(compile_kind);
                        let (file_types, _unsupported) = target_data
                            .info(*compile_kind)
                            .rustc_outputs(mode, target.kind(), triple, clean_ctx.gctx)?;
                        let artifact_dir = layout
                            .artifact_dir()
                            .expect("artifact-dir was not locked during clean");
                        let uplift_dir = match target.kind() {
                            TargetKind::ExampleBin | TargetKind::ExampleLib(..) => {
                                Some(artifact_dir.examples())
                            }
                            // Tests/benchmarks are never uplifted.
                            TargetKind::Test | TargetKind::Bench => None,
                            _ => Some(artifact_dir.dest()),
                        };
                        if let Some(uplift_dir) = uplift_dir {
                            for file_type in file_types {
                                let uplifted_filename = file_type.uplift_filename(target);

                                // Dep-info generated by Cargo itself.
                                let dep_info = Path::new(&uplifted_filename)
                                    .with_extension("d")
                                    .to_string_lossy()
                                    .into_owned();

                                dirs_to_clean.mark_utf(uplift_dir, |filename| {
                                    filename == uplifted_filename || filename == dep_info
                                });
                            }
                        }
                        let path_dash = format!("{}-", crate_name);

                        dirs_to_clean.mark_utf(layout.build_dir().incremental(), |filename| {
                            filename.starts_with(&path_dash)
                        });
                    }
                }
            }
        }
    } else {
        for pkg in packages {
            clean_ctx.progress.on_cleaning_package(&pkg.name())?;

            // Clean fingerprints.
            for (_, layout) in &layouts_with_host {
                dirs_to_clean.mark_utf(layout.build_dir().legacy_fingerprint(), |filename| {
                    let Some((pkg_name, _)) = filename.rsplit_once('-') else {
                        return false;
                    };

                    pkg_name == pkg.name().as_str()
                });
            }

            for target in pkg.targets() {
                if target.is_custom_build() {
                    // Get both the build_script_build and the output directory.
                    for (_, layout) in &layouts_with_host {
                        dirs_to_clean.mark_utf(layout.build_dir().build(), |filename| {
                            let Some((current_name, _)) = filename.rsplit_once('-') else {
                                return false;
                            };

                            current_name == pkg.name().as_str()
                        });
                    }
                    continue;
                }
                let crate_name: Rc<str> = target.crate_name().into();
                let path_dot: &str = &format!("{crate_name}.");
                let path_dash: &str = &format!("{crate_name}-");
                for &mode in &[
                    CompileMode::Build,
                    CompileMode::Test,
                    CompileMode::Check { test: false },
                ] {
                    for (compile_kind, layout) in &layouts {
                        let triple = target_data.short_name(compile_kind);
                        let (file_types, _unsupported) = target_data
                            .info(*compile_kind)
                            .rustc_outputs(mode, target.kind(), triple, clean_ctx.gctx)?;
                        let artifact_dir = layout
                            .artifact_dir()
                            .expect("artifact-dir was not locked during clean");
                        let (dir, uplift_dir) = match target.kind() {
                            TargetKind::ExampleBin | TargetKind::ExampleLib(..) => {
                                (layout.build_dir().examples(), Some(artifact_dir.examples()))
                            }
                            // Tests/benchmarks are never uplifted.
                            TargetKind::Test | TargetKind::Bench => {
                                (layout.build_dir().legacy_deps(), None)
                            }
                            _ => (layout.build_dir().legacy_deps(), Some(artifact_dir.dest())),
                        };

                        for file_type in file_types {
                            // Some files include a hash in the filename, some don't.
                            let (prefix, suffix) = file_type.output_prefix_suffix(target);
                            let unhashed_name = file_type.output_filename(target, None);
                            dirs_to_clean.mark_utf(&dir, |filename| {
                                (filename.starts_with(&prefix) && filename.ends_with(&suffix))
                                    || unhashed_name == filename
                            });

                            // Remove the uplifted copy.
                            if let Some(uplift_dir) = uplift_dir {
                                let uplifted_path =
                                    uplift_dir.join(file_type.uplift_filename(target));
                                clean_ctx.rm_rf(&uplifted_path)?;
                                // Dep-info generated by Cargo itself.
                                let dep_info = uplifted_path.with_extension("d");
                                clean_ctx.rm_rf(&dep_info)?;
                            }
                        }
                        let unhashed_dep_info = format!("{}.d", crate_name);
                        dirs_to_clean.mark_utf(dir, |filename| filename == unhashed_dep_info);

                        dirs_to_clean.mark_utf(dir, |filename| {
                            if filename.starts_with(&path_dash) {
                                // Remove dep-info file generated by rustc. It is not tracked in
                                // file_types. It does not have a prefix.
                                filename.ends_with(".d")
                            } else if filename.starts_with(&path_dot) {
                                // Remove split-debuginfo files generated by rustc.
                                [".o", ".dwo", ".dwp"]
                                    .iter()
                                    .any(|suffix| filename.ends_with(suffix))
                            } else {
                                false
                            }
                        });

                        // TODO: what to do about build_script_build?
                        dirs_to_clean.mark_utf(layout.build_dir().incremental(), |filename| {
                            filename.starts_with(path_dash)
                        });
                    }
                }
            }
        }
    }
    clean_ctx.rm_rf_all(dirs_to_clean)?;

    Ok(())
}

#[derive(Default)]
struct DirectoriesToClean {
    dir_contents: IndexMap<PathBuf, IndexSet<OsString>>,
    to_remove: IndexSet<PathBuf>,
}

impl DirectoriesToClean {
    fn mark(&mut self, directory: &Path, mut should_remove_entry: impl FnMut(&OsString) -> bool) {
        let entry = match self.dir_contents.entry(directory.to_owned()) {
            indexmap::map::Entry::Occupied(occupied_entry) => occupied_entry.into_mut(),
            indexmap::map::Entry::Vacant(vacant_entry) => {
                let Ok(dir_entries) = std::fs::read_dir(directory.to_owned()) else {
                    return;
                };
                vacant_entry.insert(
                    dir_entries
                        .into_iter()
                        .flatten()
                        .map(|entry| entry.file_name())
                        .collect::<IndexSet<_>>(),
                )
            }
        };

        entry.retain(|path| {
            let should_remove = should_remove_entry(path);
            if should_remove {
                self.to_remove.insert(directory.join(path));
            }
            !should_remove
        });
    }

    fn mark_utf(&mut self, directory: &Path, mut should_remove_entry: impl FnMut(&str) -> bool) {
        self.mark(directory, move |filename| {
            let Some(as_utf) = filename.to_str() else {
                return false;
            };
            should_remove_entry(as_utf)
        });
    }
}

impl<'gctx> CleanContext<'gctx> {
    pub fn new(gctx: &'gctx GlobalContext) -> Self {
        // This progress bar will get replaced, this is just here to avoid needing
        // an Option until the actual bar is created.
        let progress = CleaningFolderBar::new(gctx, 0);
        CleanContext {
            gctx,
            progress: Box::new(progress),
            dry_run: false,
            num_files_removed: 0,
            num_dirs_removed: 0,
            total_bytes_removed: 0,
        }
    }

    fn rm_rf_all(&mut self, dirs: DirectoriesToClean) -> CargoResult<()> {
        for path in dirs.to_remove {
            self.rm_rf(&path)?;
        }
        Ok(())
    }

    pub fn rm_rf(&mut self, path: &Path) -> CargoResult<()> {
        let meta = match fs::symlink_metadata(path) {
            Ok(meta) => meta,
            Err(e) => {
                if e.kind() != std::io::ErrorKind::NotFound {
                    self.gctx
                        .shell()
                        .warn(&format!("cannot access {}: {e}", path.display()))?;
                }
                return Ok(());
            }
        };

        // dry-run displays paths while walking, so don't print here.
        if !self.dry_run {
            self.gctx
                .shell()
                .verbose(|shell| shell.status("Removing", path.display()))?;
        }
        self.progress.display_now()?;

        let mut rm_file = |path: &Path, meta: Result<std::fs::Metadata, _>| {
            if let Ok(meta) = meta {
                // Note: This can over-count bytes removed for hard-linked
                // files. It also under-counts since it only counts the exact
                // byte sizes and not the block sizes.
                self.total_bytes_removed += meta.len();
            }
            self.num_files_removed += 1;
            if !self.dry_run {
                paths::remove_file(path)?;
            }
            Ok(())
        };

        if !meta.is_dir() {
            return rm_file(path, Ok(meta));
        }

        for entry in walkdir::WalkDir::new(path).contents_first(true) {
            let entry = entry?;
            self.progress.on_clean()?;
            if self.dry_run {
                // This prints the path without the "Removing" status since I feel
                // like it can be surprising or even frightening if cargo says it
                // is removing something without actually removing it. And I can't
                // come up with a different verb to use as the status.
                self.gctx
                    .shell()
                    .verbose(|shell| Ok(writeln!(shell.out(), "{}", entry.path().display())?))?;
            }
            if entry.file_type().is_dir() {
                self.num_dirs_removed += 1;
                // The contents should have been removed by now, but sometimes a race condition is hit
                // where other files have been added by the OS. `paths::remove_dir_all` also falls back
                // to `std::fs::remove_dir_all`, which may be more reliable than a simple walk in
                // platform-specific edge cases.
                if !self.dry_run {
                    paths::remove_dir_all(entry.path())?;
                }
            } else {
                rm_file(entry.path(), entry.metadata())?;
            }
        }

        Ok(())
    }

    pub fn display_summary(&self) -> CargoResult<()> {
        let status = if self.dry_run { "Summary" } else { "Removed" };
        let byte_count = if self.total_bytes_removed == 0 {
            String::new()
        } else {
            let bytes = HumanBytes(self.total_bytes_removed);
            format!(", {bytes:.1} total")
        };
        // I think displaying the number of directories removed isn't
        // particularly interesting to the user. However, if there are 0
        // files, and a nonzero number of directories, cargo should indicate
        // that it did *something*, so directory counts are only shown in that
        // case.
        let file_count = match (self.num_files_removed, self.num_dirs_removed) {
            (0, 0) => format!("0 files"),
            (0, 1) => format!("1 directory"),
            (0, 2..) => format!("{} directories", self.num_dirs_removed),
            (1, _) => format!("1 file"),
            (2.., _) => format!("{} files", self.num_files_removed),
        };
        self.gctx
            .shell()
            .status(status, format!("{file_count}{byte_count}"))?;
        if self.dry_run {
            self.gctx
                .shell()
                .warn("no files deleted due to --dry-run")?;
        }
        Ok(())
    }

    /// Deletes all of the given paths, showing a progress bar as it proceeds.
    ///
    /// If any path does not exist, or is not accessible, this will not
    /// generate an error. This only generates an error for other issues, like
    /// not being able to write to the console.
    pub fn remove_paths(&mut self, paths: &[PathBuf]) -> CargoResult<()> {
        let num_paths = paths
            .iter()
            .map(|path| walkdir::WalkDir::new(path).into_iter().count())
            .sum();
        self.progress = Box::new(CleaningFolderBar::new(self.gctx, num_paths));
        for path in paths {
            self.rm_rf(path)?;
        }
        Ok(())
    }
}

trait CleaningProgressBar {
    fn display_now(&mut self) -> CargoResult<()>;
    fn on_clean(&mut self) -> CargoResult<()>;
    fn on_cleaning_package(&mut self, _package: &str) -> CargoResult<()> {
        Ok(())
    }
}

struct CleaningFolderBar<'gctx> {
    bar: Progress<'gctx>,
    max: usize,
    cur: usize,
}

impl<'gctx> CleaningFolderBar<'gctx> {
    fn new(gctx: &'gctx GlobalContext, max: usize) -> Self {
        Self {
            bar: Progress::with_style("Cleaning", ProgressStyle::Percentage, gctx),
            max,
            cur: 0,
        }
    }

    fn cur_progress(&self) -> usize {
        std::cmp::min(self.cur, self.max)
    }
}

impl<'gctx> CleaningProgressBar for CleaningFolderBar<'gctx> {
    fn display_now(&mut self) -> CargoResult<()> {
        self.bar.tick_now(self.cur_progress(), self.max, "")
    }

    fn on_clean(&mut self) -> CargoResult<()> {
        self.cur += 1;
        self.bar.tick(self.cur_progress(), self.max, "")
    }
}

struct CleaningPackagesBar<'gctx> {
    bar: Progress<'gctx>,
    max: usize,
    cur: usize,
    num_files_folders_cleaned: usize,
    package_being_cleaned: String,
}

impl<'gctx> CleaningPackagesBar<'gctx> {
    fn new(gctx: &'gctx GlobalContext, max: usize) -> Self {
        Self {
            bar: Progress::with_style("Cleaning", ProgressStyle::Ratio, gctx),
            max,
            cur: 0,
            num_files_folders_cleaned: 0,
            package_being_cleaned: String::new(),
        }
    }

    fn cur_progress(&self) -> usize {
        std::cmp::min(self.cur, self.max)
    }

    fn format_message(&self) -> String {
        format!(
            ": {}, {} files/folders cleaned",
            self.package_being_cleaned, self.num_files_folders_cleaned
        )
    }
}

impl<'gctx> CleaningProgressBar for CleaningPackagesBar<'gctx> {
    fn display_now(&mut self) -> CargoResult<()> {
        self.bar
            .tick_now(self.cur_progress(), self.max, &self.format_message())
    }

    fn on_clean(&mut self) -> CargoResult<()> {
        self.bar
            .tick(self.cur_progress(), self.max, &self.format_message())?;
        self.num_files_folders_cleaned += 1;
        Ok(())
    }

    fn on_cleaning_package(&mut self, package: &str) -> CargoResult<()> {
        self.cur += 1;
        self.package_being_cleaned = String::from(package);
        self.bar
            .tick(self.cur_progress(), self.max, &self.format_message())
    }
}
