//! Bookmarks (spec §10.1): named states, any number per repository, with a
//! current bookmark per workspace. Merging is the union of two bookmarks'
//! heads: no merge change, conflicts reified.

use super::*;

/// One bookmark as `oxy bookmark list` shows it.
#[derive(Clone, Debug)]
pub struct BookmarkInfo {
    pub name: String,
    pub heads: Vec<ChangeHash>,
    /// The workspace's current bookmark.
    pub current: bool,
    /// Changes ahead of / behind `origin`'s copy, when tracked.
    pub ahead: Option<usize>,
    pub behind: Option<usize>,
}

#[derive(Clone, Debug)]
pub struct MergeReport {
    pub heads: Vec<ChangeHash>,
    pub changed: bool,
    pub checked_out: bool,
}

/// Bookmark and tag names (spec §10.1): UTF-8, 1–255 bytes, no control
/// characters, no leading `-`, and none of `..`, `//`, `@{`.
pub fn valid_reference_name(name: &str) -> bool {
    !name.is_empty()
        && name.len() <= 255
        && !name.starts_with('-')
        && !name.chars().any(|c| c.is_control())
        && !name.contains("..")
        && !name.contains("//")
        && !name.contains("@{")
        && name != "policy"
}

impl Repo {
    fn workspace_bookmark_path(&self) -> PathBuf {
        self.oxy
            .join("workspaces")
            .join(self.workspace.to_hex())
            .join("bookmark")
    }

    /// Every bookmark with its heads and remote-tracking difference.
    pub fn bookmarks(&self) -> Result<Vec<BookmarkInfo>> {
        let view = self.view()?;
        let mut out = Vec::new();
        for (name, st) in &view.bookmarks {
            let heads = self.store.get_state(st)?.heads;
            let (ahead, behind) = match view.remotes.get("origin").and_then(|b| b.get(name)) {
                Some(rs) => {
                    let remote_heads = self.store.get_state(rs)?.heads;
                    (
                        self.negotiate(&remote_heads, &heads).map(|v| v.len()).ok(),
                        self.negotiate(&heads, &remote_heads).map(|v| v.len()).ok(),
                    )
                }
                None => (None, None),
            };
            out.push(BookmarkInfo {
                name: name.clone(),
                heads,
                current: *name == self.config.bookmark,
                ahead,
                behind,
            });
        }
        Ok(out)
    }

    /// Create `name` at `heads` (default: the working copy's base heads).
    pub fn bookmark_create(
        &self,
        name: &str,
        heads: Option<&[ChangeHash]>,
    ) -> Result<Vec<ChangeHash>> {
        if !valid_reference_name(name) {
            return fail(format!("{name:?} is not a valid bookmark name"));
        }
        let (op_ref, op) = self.head_op()?;
        if op.view.bookmarks.contains_key(name) {
            return fail(format!("bookmark {name} already exists"));
        }
        let heads = match heads {
            Some(h) => self.load_state(h)?.maximal(h),
            None => {
                let (_, wc) = self.working_copy()?;
                self.load_state(&wc.deps)?.maximal(&wc.deps)
            }
        };
        let mut view = op.view.clone();
        view.bookmarks.insert(
            name.to_string(),
            self.store.put_state(&StateObject::new(heads.clone()))?,
        );
        self.record_op(&[op_ref], &format!("oxy bookmark create {name}"), view)?;
        Ok(heads)
    }

    /// Point an existing bookmark at `heads`.
    pub fn bookmark_set(&self, name: &str, heads: &[ChangeHash]) -> Result<Vec<ChangeHash>> {
        let (op_ref, op) = self.head_op()?;
        if !op.view.bookmarks.contains_key(name) {
            return fail(format!(
                "no bookmark {name}; create it with `oxy bookmark create`"
            ));
        }
        let heads = self.load_state(heads)?.maximal(heads);
        let mut view = op.view.clone();
        view.bookmarks.insert(
            name.to_string(),
            self.store.put_state(&StateObject::new(heads.clone()))?,
        );
        self.record_op(&[op_ref], &format!("oxy bookmark set {name}"), view)?;
        if name == self.config.bookmark {
            self.drop_manifest();
        }
        Ok(heads)
    }

    /// Remove a bookmark; its changes stay until unreachable (spec §21).
    pub fn bookmark_delete(&self, name: &str) -> Result<()> {
        if name == self.config.bookmark {
            return fail(format!(
                "{name} is this workspace's current bookmark; switch to another first"
            ));
        }
        for w in self.workspaces()? {
            if !w.current && self.workspace_bookmark_of(&w.id).as_deref() == Some(name) {
                return fail(format!(
                    "{name} is the current bookmark of workspace {} at {}",
                    w.id.short(8),
                    w.path.display()
                ));
            }
        }
        let (op_ref, op) = self.head_op()?;
        let mut view = op.view.clone();
        if view.bookmarks.remove(name).is_none() {
            return fail(format!("no bookmark {name}"));
        }
        self.record_op(&[op_ref], &format!("oxy bookmark delete {name}"), view)?;
        Ok(())
    }

    fn workspace_bookmark_of(&self, id: &WorkspaceId) -> Option<String> {
        fs::read_to_string(
            self.oxy
                .join("workspaces")
                .join(id.to_hex())
                .join("bookmark"),
        )
        .ok()
        .map(|s| s.trim().to_string())
        .filter(|s| !s.is_empty())
    }

    /// Make `name` this workspace's current bookmark and check it out.
    pub fn bookmark_switch(&mut self, name: &str, discard: bool) -> Result<CheckoutReport> {
        let view = self.view()?;
        let Some(st) = view.bookmarks.get(name) else {
            return fail(format!("no bookmark {name}"));
        };
        let heads = self.store.get_state(st)?.heads;
        let report = self.checkout(&heads, discard, &format!("oxy bookmark switch {name}"))?;
        fs::create_dir_all(self.workspace_bookmark_path().parent().unwrap())?;
        write_atomic(&self.workspace_bookmark_path(), name.as_bytes())?;
        self.config.bookmark = name.to_string();
        Ok(report)
    }

    /// Record `name` as the current bookmark of a new workspace.
    pub(crate) fn set_workspace_bookmark(&self, id: &WorkspaceId, name: &str) -> Result<()> {
        let dir = self.oxy.join("workspaces").join(id.to_hex());
        fs::create_dir_all(&dir)?;
        write_atomic(&dir.join("bookmark"), name.as_bytes())
    }

    /// Union the heads of bookmark `name` into the current bookmark (spec
    /// §10.1). The working copy follows when it was clean on the old heads.
    pub fn merge(&self, name: &str) -> Result<MergeReport> {
        let (op_ref, op) = self.head_op()?;
        let current = self.config.bookmark.clone();
        if name == current {
            return fail(format!("{name} is the current bookmark"));
        }
        let Some(st) = op.view.bookmarks.get(name) else {
            return fail(format!("no bookmark {name}"));
        };
        let other = self.store.get_state(st)?.heads;
        let local = self.heads_of(&op.view, &current)?;
        let mut all = local.clone();
        all.extend(other);
        let mut heads = self.load_state(&all)?.maximal(&all);
        heads.sort();
        let mut sorted_local = local.clone();
        sorted_local.sort();
        if heads == sorted_local {
            return Ok(MergeReport {
                heads,
                changed: false,
                checked_out: false,
            });
        }
        let mut view = op.view.clone();
        view.bookmarks.insert(
            current,
            self.store.put_state(&StateObject::new(heads.clone()))?,
        );
        self.record_op(&[op_ref], &format!("oxy merge {name}"), view)?;
        let snap = self.snapshot("oxy merge")?;
        let clean = snap.wc.tree_ops.is_empty() && snap.wc.edits.is_empty();
        let mut base = snap.base.maximal(&snap.wc.deps);
        base.sort();
        let mut checked_out = false;
        if clean && base == sorted_local {
            self.checkout(&heads, false, "oxy merge (checkout)")?;
            checked_out = true;
        }
        Ok(MergeReport {
            heads,
            changed: true,
            checked_out,
        })
    }
}