//! Subrepositories in the working copy (spec §7.8): reading pins from

//! nested repositories, moving them to pins, and the `oxy submodule`

//! commands.

use super::*;

use crate::subrepo::{Module, Modules, Pin};

use std::process::Command;

/// What syncing a nested repository to its pin did.

#[derive(Clone, Debug, PartialEq, Eq)]

pub enum SubrepoSync {

    Updated,

    UpToDate,

    Missing,

    Dirty,

    /// The working copy was brought to the pin, but the nested repository's

    /// bookmark has changes the pin lacks, so it was left where it is: a

    /// bookmark is never moved backwards (spec §7.8).

    KeptBookmark {

        bookmark: String,

        newer: usize,

    },

    Failed(String),

}

impl SubrepoSync {

    /// A note for a checkout report, when there is something to say.

    pub fn note(&self, path: &str) -> Option<String> {

        match self {

            SubrepoSync::Updated | SubrepoSync::UpToDate => None,

            SubrepoSync::Missing => Some(format!(

                "{path}: nested repository not present; run oxy submodule update --init"

            )),

            SubrepoSync::Dirty => Some(format!(

                "{path}: nested repository has uncommitted changes; left as is"

            )),

            SubrepoSync::KeptBookmark { bookmark, newer } => Some(format!(

                "{path}: checked out at the pin; its bookmark {bookmark} keeps {newer} newer change{} (oxy bookmark switch {bookmark} there to return to them)",

                if *newer == 1 { "" } else { "s" }

            )),

            SubrepoSync::Failed(e) => Some(format!("{path}: {e}")),

        }

    }

}

/// One subrepo as `oxy submodule status` shows it.

#[derive(Clone, Debug)]

pub struct SubrepoInfo {

    pub path: String,

    pub pin: Pin,

    pub url: Option<String>,

    /// The nested repository's own pin now, if present.

    pub actual: Option<Pin>,

    pub dirty: bool,

    /// Whether the working copy's base records it. An added subrepo

    /// (registered in `.oxymodules`, not committed yet) has `pin` set to

    /// what the next commit records.

    pub committed: bool,

}

fn git_out(dir: &Path, args: &[&str]) -> Result<String> {

    let out = Command::new("git")

        .arg("-C")

        .arg(dir)

        .args(args)

        .output()

        .map_err(|e| RepoError::Msg(format!("running git: {e}")))?;

    if !out.status.success() {

        return fail(format!(

            "git {} in {}: {}",

            args.join(" "),

            dir.display(),

            String::from_utf8_lossy(&out.stderr).trim()

        ));

    }

    Ok(String::from_utf8_lossy(&out.stdout).trim().to_string())

}

/// The pin a nested repository at `dir` is at: the base of its working

/// copy for an Oxygen repository (which is its bookmark's heads unless a

/// parent checked out an older pin), `HEAD` for a Git one.

pub(crate) fn read_pin(dir: &Path, bookmark_hint: Option<&str>) -> Result<Pin> {

    if dir.join(OXY_DIR).exists() {

        let nested = Repo::open(dir)?;

        return Ok(Pin::Oxy {

            repo: nested.id()?,

            heads: nested.working_copy()?.1.deps,

            bookmark: nested.config.bookmark.clone(),

        });

    }

    if dir.join(".git").exists() {

        let sha = git_out(dir, &["rev-parse", "HEAD"])?;

        return Ok(Pin::Git {

            sha,

            branch: bookmark_hint.unwrap_or("HEAD").to_string(),

        });

    }

    fail(format!("{} is not a repository", dir.display()))

}

/// Whether a nested repository has uncommitted work.

fn nested_dirty(dir: &Path) -> Result<bool> {

    if dir.join(OXY_DIR).exists() {

        let nested = Repo::open(dir)?;

        let snap = nested.snapshot("oxy submodule")?;

        return Ok(!snap.wc.tree_ops.is_empty() || !snap.wc.edits.is_empty());

    }

    Ok(!git_out(dir, &["status", "--porcelain"])?.is_empty())

}

/// Whether `url` names an Oxygen repository (else it is taken to be Git).

fn is_oxy_url(url: &str) -> bool {

    if url.starts_with("http://") || url.starts_with("https://") {

        return crate::protocol::open_remote(url, &RemoteOptions::default())

            .and_then(|r| r.repo_id())

            .is_ok();

    }

    let p = Path::new(url.strip_prefix("file://").unwrap_or(url));

    p.join(OXY_DIR).exists()

}

impl Repo {

    pub(crate) fn modules_on_disk(&self) -> Modules {

        fs::read_to_string(self.root.join(".oxymodules"))

            .map(|t| Modules::parse(&t))

            .unwrap_or_default()

    }

    fn write_modules(&self, m: &Modules) -> Result<()> {

        if m.entries.is_empty() {

            let _ = fs::remove_file(self.root.join(".oxymodules"));

            return Ok(());

        }

        write_atomic(&self.root.join(".oxymodules"), m.to_text().as_bytes())

    }

    /// Bring the nested repository at `path` to `pin`, cloning it first when

    /// `init` and it is absent.

    pub(crate) fn sync_subrepo(&self, path: &str, pin: &Pin, init: bool) -> Result<SubrepoSync> {

        let dir = self.root.join(path);

        let module = self.modules_on_disk().entries.get(path).cloned();

        let present = dir.join(OXY_DIR).exists() || dir.join(".git").exists();

        let cloned = !present;

        if !present {

            if !init {

                return Ok(SubrepoSync::Missing);

            }

            let Some(m) = &module else {

                return Ok(SubrepoSync::Failed(

                    "no .oxymodules entry to clone from".into(),

                ));

            };

            if let Some(parent) = dir.parent() {

                fs::create_dir_all(parent)?;

            }

            let _ = fs::remove_dir(&dir);

            let r = match pin {

                Pin::Oxy { .. } => Repo::clone(&m.url, &dir).map(|_| ()),

                Pin::Git { .. } => Command::new("git")

                    .args(["clone", "-q", &m.url])

                    .arg(&dir)

                    .status()

                    .map_err(|e| RepoError::Msg(e.to_string()))

                    .and_then(|s| {

                        if s.success() {

                            Ok(())

                        } else {

                            fail(format!("git clone {} failed", m.url))

                        }

                    }),

            };

            if let Err(e) = r {

                return Ok(SubrepoSync::Failed(format!("cloning {}: {e}", m.url)));

            }

        }

        let actual = read_pin(&dir, module.as_ref().and_then(|m| m.bookmark.as_deref()))?;

        let same = match (pin, &actual) {

            (Pin::Oxy { heads: a, .. }, Pin::Oxy { heads: b, .. }) => {

                let (mut a, mut b) = (a.clone(), b.clone());

                a.sort();

                b.sort();

                a == b

            }

            (Pin::Git { sha: a, .. }, Pin::Git { sha: b, .. }) => a == b,

            _ => false,

        };

        if same {

            return Ok(if cloned {

                SubrepoSync::Updated

            } else {

                SubrepoSync::UpToDate

            });

        }

        if nested_dirty(&dir)? {

            return Ok(SubrepoSync::Dirty);

        }

        match pin {

            Pin::Oxy { heads, .. } => {

                let nested = Repo::open(&dir)?;

                if nested.load_state(heads).is_err() {

                    // The pinned changes are not here yet: fetch from origin.

                    if let Err(e) = nested.fetch("origin") {

                        return Ok(SubrepoSync::Failed(format!(

                            "fetching the pinned changes: {e}"

                        )));

                    }

                }

                match nested.checkout(heads, false, "oxy submodule update") {

                    Ok(_) => {

                        // Its bookmark follows only forward: work it has

                        // beyond the pin stays on it (metalgear, oxygen#38).

                        let bookmark = nested.config.bookmark.clone();

                        let at = nested.bookmark_heads().unwrap_or_default();

                        let newer = nested.state_gap(&at, heads).map(|g| g.lacks).unwrap_or(0);

                        if newer == 0 {

                            let _ = nested.bookmark_set(&bookmark, heads);

                            Ok(SubrepoSync::Updated)

                        } else {

                            Ok(SubrepoSync::KeptBookmark { bookmark, newer })

                        }

                    }

                    Err(e) => Ok(SubrepoSync::Failed(e.to_string())),

                }

            }

            Pin::Git { sha, .. } => {

                if git_out(&dir, &["cat-file", "-e", &format!("{sha}^{{commit}}")]).is_err() {

                    if let Err(e) = git_out(&dir, &["fetch", "-q", "origin"]) {

                        return Ok(SubrepoSync::Failed(e.to_string()));

                    }

                }

                match git_out(&dir, &["checkout", "-q", "--detach", sha]) {

                    Ok(_) => Ok(SubrepoSync::Updated),

                    Err(e) => Ok(SubrepoSync::Failed(e.to_string())),

                }

            }

        }

    }

    /// Every subrepo of the working copy's base state.

    pub fn subrepos(&self) -> Result<Vec<SubrepoInfo>> {

        let (_, wc) = self.working_copy()?;

        let snap = self.load_state(&wc.deps)?.materialize();

        let modules = self.modules_on_disk();

        let mut out = Vec::new();

        for (path, f) in &snap.files {

            if f.kind != NodeKind::Subrepo {

                continue;

            }

            let FileContent::Opaque { blobs } = &f.content else {

                continue;

            };

            let Some(b) = blobs.first() else { continue };

            let pin = Pin::decode(&self.read_blob(b)?)?;

            let dir = self.root.join(path);

            let present = dir.join(OXY_DIR).exists() || dir.join(".git").exists();

            let actual = if present {

                read_pin(

                    &dir,

                    modules

                        .entries

                        .get(path)

                        .and_then(|m| m.bookmark.as_deref()),

                )

                .ok()

            } else {

                None

            };

            let dirty = present && nested_dirty(&dir).unwrap_or(false);

            out.push(SubrepoInfo {

                path: path.clone(),

                pin,

                url: modules.entries.get(path).map(|m| m.url.clone()),

                actual,

                dirty,

                committed: true,

            });

        }

        // Registered but not committed yet: pinned at what they are now.

        for (path, m) in &modules.entries {

            if snap.files.contains_key(path) {

                continue;

            }

            let dir = self.root.join(path);

            let Ok(pin) = read_pin(&dir, m.bookmark.as_deref()) else {

                continue;

            };

            out.push(SubrepoInfo {

                path: path.clone(),

                pin: pin.clone(),

                url: Some(m.url.clone()),

                actual: Some(pin),

                dirty: nested_dirty(&dir).unwrap_or(false),

                committed: false,

            });

        }

        out.sort_by(|a, b| a.path.cmp(&b.path));

        Ok(out)

    }

    /// Clone `url` at `path`, register it in `.oxymodules`, and return the

    /// pin the next snapshot will record.

    pub fn submodule_add(&self, url: &str, path: &str, bookmark: Option<&str>) -> Result<Pin> {

        let path = path.trim_end_matches('/').to_string();

        if path.is_empty()

            || path.starts_with('/')

            || path.split('/').any(|c| c == ".." || c == ".")

        {

            return fail(format!("{path:?} is not a valid subrepo path"));

        }

        let dir = self.root.join(&path);

        if dir.exists() && fs::read_dir(&dir)?.next().is_some() {

            return fail(format!("{path} exists and is not empty"));

        }

        if let Some(parent) = dir.parent() {

            fs::create_dir_all(parent)?;

        }

        let git = !is_oxy_url(url);

        if git {

            let mut cmd = Command::new("git");

            cmd.args(["clone", "-q"]);

            if let Some(b) = bookmark {

                cmd.args(["--branch", b]);

            }

            let status = cmd

                .arg(url)

                .arg(&dir)

                .status()

                .map_err(|e| RepoError::Msg(format!("running git: {e}")))?;

            if !status.success() {

                return fail(format!("git clone {url} failed"));

            }

        } else {

            let _ = fs::remove_dir(&dir);

            let mut nested = Repo::clone(url, &dir)?;

            if let Some(b) = bookmark {

                nested.bookmark_switch(b, true)?;

            }

        }

        let mut modules = self.modules_on_disk();

        modules.entries.insert(

            path.clone(),

            Module {

                url: url.to_string(),

                bookmark: bookmark.map(str::to_string),

                git,

            },

        );

        self.write_modules(&modules)?;

        read_pin(&dir, bookmark)

    }

    /// Bring nested repositories to their pins (`paths` empty = all).

    pub fn submodule_update(

        &self,

        init: bool,

        paths: &[String],

    ) -> Result<Vec<(String, SubrepoSync)>> {

        let mut out = Vec::new();

        for s in self.subrepos()? {

            if !paths.is_empty() && !paths.iter().any(|p| p.trim_end_matches('/') == s.path) {

                continue;

            }

            let r = self.sync_subrepo(&s.path, &s.pin, init)?;

            out.push((s.path, r));

        }

        Ok(out)

    }

    /// Drop the `.oxymodules` entry; the node goes with the next snapshot

    /// only if the directory is removed, since a registered or tracked

    /// nested repository keeps contributing its pin. Here the directory is

    /// left in place and the node is removed explicitly from the working

    /// copy's next change by unregistering and moving the directory aside.

    pub fn submodule_remove(&self, path: &str) -> Result<()> {

        let path = path.trim_end_matches('/').to_string();

        let mut modules = self.modules_on_disk();

        let known = modules.entries.remove(&path).is_some()

            || self.subrepos()?.iter().any(|s| s.path == path);

        if !known {

            return fail(format!("{path} is not a subrepo"));

        }

        self.write_modules(&modules)?;

        // The directory stays; the walker ignores an unregistered nested

        // repository unless tracked, so mark it as removed for the next

        // snapshot by recording an explicit removal.

        let dir = self.oxy.join("subrepos-removed");

        fs::create_dir_all(&dir)?;

        write_atomic(&dir.join(path.replace('/', "%2F")), b"")?;

        Ok(())

    }

    /// Paths whose subrepo node was removed with `oxy submodule remove` and

    /// whose directory is still on disk.

    pub(crate) fn removed_subrepos(&self) -> BTreeSet<String> {

        let mut out = BTreeSet::new();

        if let Ok(rd) = fs::read_dir(self.oxy.join("subrepos-removed")) {

            for e in rd.flatten() {

                out.insert(e.file_name().to_string_lossy().replace("%2F", "/"));

            }

        }

        out

    }

    pub(crate) fn clear_removed_subrepo(&self, path: &str) {

        let _ = fs::remove_file(

            self.oxy

                .join("subrepos-removed")

                .join(path.replace('/', "%2F")),

        );

    }

}