//! A repository on disk: the `.oxy` directory, one workspace, the operation

//! log, and the working-copy change (spec §12, §13.1).

//!

//! Not yet implemented from the spec: packs, checkpoints, multiple

//! workspaces, multi-signer policy updates, and the `objects`/`checkpoint`

//! endpoints. A repository without a policy is unverified and accepts

//! unsigned pushes; with one, everything received is checked (spec §14.5). Changes are signed individually when `core.sign` is

//! `change`; the default `seal` leaves them unsigned until push exists.

use crate::attest::{Attest, AttestBody};

use crate::diff::{ranges, split_lines, text_edits};

use crate::protocol::{open_remote, Bundle, RefResult, RefUpdate, RefsResponse, RemoteOptions, RemoteRef, SignedAttest, SignedPolicy};

use crate::hash::{hash_object, ChangeHash, KeyId, ObjectRef, ObjectType};

use crate::identity::{verify as verify_signature, Domain, Identity, SecretKey, Signature};

use crate::ids::{ChangeId, NodeId, WorkspaceId};

use crate::objects::{Blob, Change, ChangeKind, Edit, Hlc, Mode, NodeKind, OpRef, StateObject, TreeOp};

use crate::oplog::{Format1Op, Op, View, SNAPSHOT_SUFFIX};

use crate::state::{FileContent, Snapshot, State};

use crate::store::{Store, StoreError};

use crate::tree::OpKey;

use rand::RngCore;

use std::collections::{BTreeMap, BTreeSet, HashMap};

use std::fs;

use std::io::Write;

use std::path::{Path, PathBuf};

pub const OXY_DIR: &str = ".oxy";

pub const FORMAT_LINE: &str = "oxy repository format 2\n";

const FORMAT1_LINE: &str = "oxy repository format 1\n";

const BINARY_SNIFF: usize = 8 * 1024;

/// Loose objects tolerated before a commit packs them (spec §13.4).

pub const AUTOPACK_THRESHOLD: usize = 4096;

#[derive(Debug, thiserror::Error)]

pub enum RepoError {

    #[error("io: {0}")]

    Io(#[from] std::io::Error),

    #[error(transparent)]

    Store(#[from] StoreError),

    #[error(transparent)]

    Object(#[from] crate::objects::ObjectError),

    #[error(transparent)]

    State(#[from] crate::state::StateError),

    #[error("{0}")]

    Msg(String),

}

pub type Result<T> = std::result::Result<T, RepoError>;

fn fail<T>(s: impl Into<String>) -> Result<T> {

    Err(RepoError::Msg(s.into()))

}

mod checkout;

mod config;

mod identity;

mod policy;

mod snapshot;

mod sync;

#[cfg(test)]

mod tests;

pub use checkout::CheckoutReport;

pub use config::{read_config_file, Config};

pub use identity::SignatureStatus;

pub use snapshot::{added_node_paths, has_conflict_markers, is_binary, referenced_changes, render_change, ChangeStatus, PathStatus, SnapshotResult};

pub use sync::{FetchReport, PullReport};

fn write_atomic(path: &Path, data: &[u8]) -> Result<()> {

    let tmp = path.with_extension("tmp");

    {

        let mut f = fs::File::create(&tmp)?;

        f.write_all(data)?;

        f.sync_all()?;

    }

    fs::rename(&tmp, path)?;

    Ok(())

}

pub struct LogEntry {

    pub hash: ChangeHash,

    pub change: Change,

    pub is_working_copy: bool,

    pub is_head: bool,

}

struct FsEntry {

    kind: NodeKind,

    exec: bool,

    content: Vec<u8>,

}

pub struct Repo {

    root: PathBuf,

    oxy: PathBuf,

    store: Store,

    workspace: WorkspaceId,

    keys_dir: PathBuf,

    user_config: PathBuf,

    pub config: Config,

}

/// The user's oxy directory: `$OXY_HOME`, else `$XDG_CONFIG_HOME/oxy`, else

/// `~/.config/oxy`. It holds `config.toml` (spec §19) and `keys/`.

pub fn default_home() -> PathBuf {

    if let Ok(h) = std::env::var("OXY_HOME") {

        return PathBuf::from(h);

    }

    if let Ok(x) = std::env::var("XDG_CONFIG_HOME") {

        return PathBuf::from(x).join("oxy");

    }

    let home = std::env::var("HOME").unwrap_or_else(|_| ".".into());

    PathBuf::from(home).join(".config").join("oxy")

}

pub fn default_keys_dir() -> PathBuf {

    default_home().join("keys")

}

pub fn default_user_config() -> PathBuf {

    default_home().join("config.toml")

}

/// Where `create_identity` records the author.

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

pub enum IdentityScope {

    /// The user file: every repository of this user signs with it.

    User,

    /// This repository only.

    Repo,

}

impl Repo {

    // ------------------------------------------------------------ lifecycle

    pub fn init(root: &Path) -> Result<Repo> {

        let mut id = [0u8; 16];

        rand::rngs::OsRng.fill_bytes(&mut id);

        Self::init_with_id(root, id)

    }

    /// Initialize a repository with a given repository ID (clones share the

    /// ID of their origin, spec §14.4).

    pub fn init_with_id(root: &Path, id: [u8; 16]) -> Result<Repo> {

        fs::create_dir_all(root)?;

        let root = root.canonicalize().unwrap_or_else(|_| root.to_path_buf());

        let oxy = root.join(OXY_DIR);

        if oxy.exists() {

            return fail(format!("{} is already an oxy repository", root.display()));

        }

        fs::create_dir_all(oxy.join("ops"))?;

        write_atomic(&oxy.join("format"), FORMAT_LINE.as_bytes())?;

        write_atomic(&oxy.join("id"), hex::encode(id).as_bytes())?;

        let config = Config::load(Some(&default_user_config()), &oxy.join("config"))?;

        config.save(&oxy.join("config"))?;

        let workspace = WorkspaceId::random();

        write_atomic(&oxy.join("workspace"), workspace.to_hex().as_bytes())?;

        let store = Store::open(oxy.join("objects"))?;

        let repo = Repo { root, oxy, store, workspace, keys_dir: default_keys_dir(), user_config: default_user_config(), config };

        let wc = repo.new_working_copy(vec![], "");

        let wc_hash = repo.store.put_change(&wc)?;

        let mut view = View::default();

        view.bookmarks.insert(repo.config.bookmark.clone(), repo.store.put_state(&StateObject::new(vec![]))?);

        view.workspaces.insert(workspace, wc_hash);

        repo.record_op(&[], "oxy init", view)?;

        Ok(repo)

    }

    /// Open the repository containing `start` (searching upwards).

    pub fn open(start: &Path) -> Result<Repo> {

        let start = start.canonicalize()?;

        let mut dir: Option<&Path> = Some(&start);

        while let Some(d) = dir {

            let oxy = d.join(OXY_DIR);

            if oxy.is_dir() {

                let format = fs::read_to_string(oxy.join("format"))?;

                let config = Config::load(Some(&default_user_config()), &oxy.join("config"))?;

                let workspace = WorkspaceId::from_hex(fs::read_to_string(oxy.join("workspace"))?.trim())

                    .ok_or_else(|| RepoError::Msg("corrupt .oxy/workspace".into()))?;

                let store = Store::open(oxy.join("objects"))?;

                let repo = Repo { root: d.to_path_buf(), oxy, store, workspace, keys_dir: default_keys_dir(), user_config: default_user_config(), config };

                if format == FORMAT1_LINE {

                    repo.migrate_format1()?;

                } else if format != FORMAT_LINE {

                    return fail(format!("unsupported repository format: {}", format.trim()));

                }

                return Ok(repo);

            }

            dir = d.parent();

        }

        fail(format!("no oxy repository found at or above {}", start.display()))

    }

    /// Rewrite a format-1 operation log, whose bookmarks were head lists,

    /// into format 2, where each bookmark names a `state` object.

    fn migrate_format1(&self) -> Result<()> {

        let hex = fs::read_to_string(self.oxy.join("ops").join("head"))?;

        let head = ObjectRef::from_hex(hex.trim()).ok_or_else(|| RepoError::Msg("corrupt .oxy/ops/head".into()))?;

        // Collect the chain root-first.

        let mut chain: Vec<Format1Op> = Vec::new();

        let mut cur = Some(head);

        while let Some(r) = cur {

            let op = Op::decode_format1(&self.store.get_typed(&r, ObjectType::Op)?)?;

            cur = op.parents.first().copied();

            chain.push(op);

        }

        chain.reverse();

        let mut new_parent: Option<ObjectRef> = None;

        for old in chain {

            let mut view = View::default();

            for (name, heads) in &old.view.bookmarks {

                view.bookmarks.insert(name.clone(), self.store.put_state(&StateObject::new(heads.clone()))?);

            }

            view.workspaces = old.view.workspaces.clone();

            let op = Op { parents: new_parent.into_iter().collect(), hlc: old.hlc, command: old.command, view };

            new_parent = Some(self.store.put(ObjectType::Op, &op.encode())?);

        }

        write_atomic(&self.oxy.join("ops").join("head"), new_parent.unwrap().to_hex().as_bytes())?;

        write_atomic(&self.oxy.join("format"), FORMAT_LINE.as_bytes())?;

        Ok(())

    }

    /// Pack every loose object (spec §13.4). Pruning unreachable objects

    /// waits for operation-log retention, since every operation keeps its

    /// states reachable for now.

    pub fn gc(&self) -> Result<crate::store::PackReport> {

        Ok(self.store.pack_loose()?)

    }

    /// Pack automatically once many loose objects have accumulated.

    pub(crate) fn maybe_autopack(&self) -> Result<()> {

        if self.store.loose_count()? > AUTOPACK_THRESHOLD {

            self.store.pack_loose()?;

        }

        Ok(())

    }

    /// The repository ID (spec §14.4). Repositories made before IDs existed get one on first use.

    pub fn id(&self) -> Result<[u8; 16]> {

        let path = self.oxy.join("id");

        match fs::read_to_string(&path) {

            Ok(h) => hex::decode(h.trim()).ok().and_then(|v| v.try_into().ok()).ok_or_else(|| RepoError::Msg("corrupt .oxy/id".into())),

            Err(e) if e.kind() == std::io::ErrorKind::NotFound => {

                let mut id = [0u8; 16];

                rand::rngs::OsRng.fill_bytes(&mut id);

                write_atomic(&path, hex::encode(id).as_bytes())?;

                Ok(id)

            }

            Err(e) => Err(e.into()),

        }

    }

    pub fn root(&self) -> &Path {

        &self.root

    }

    pub fn store(&self) -> &Store {

        &self.store

    }

    pub fn workspace(&self) -> WorkspaceId {

        self.workspace

    }

    /// Use a different user directory for keys and the user config file

    /// (tests, or `$OXY_HOME`). Reloads the effective configuration.

    pub fn with_home(mut self, dir: impl Into<PathBuf>) -> Repo {

        let dir = dir.into();

        self.keys_dir = dir.join("keys");

        self.user_config = dir.join("config.toml");

        if let Ok(c) = Config::load(Some(&self.user_config), &self.oxy.join("config")) {

            self.config = c;

        }

        self

    }

    pub fn user_config_path(&self) -> &Path {

        &self.user_config

    }

    /// Set a key in the user file and refresh the effective configuration.

    pub fn set_user_config(&mut self, key: &str, value: &str) -> Result<()> {

        Config::set_user(&self.user_config, key, value)?;

        self.config = Config::load(Some(&self.user_config), &self.oxy.join("config"))?;

        Ok(())

    }

    pub fn save_config(&self) -> Result<()> {

        self.config.save(&self.oxy.join("config"))

    }

    fn author(&self) -> KeyId {

        self.config.author_key.unwrap_or(ObjectRef::ZERO)

    }

}

impl Repo {

    fn new_working_copy(&self, deps: Vec<ChangeHash>, message: &str) -> Change {

        let mut c = Change {

            change_id: ChangeId::random(),

            deps,

            author: self.author(),

            hlc: Hlc::now(),

            message: message.into(),

            tree_ops: vec![],

            edits: vec![],

            kind: ChangeKind::WorkingCopy,

        };

        c.normalize();

        c

    }

    // ------------------------------------------------------------ operation log

    pub fn head_op(&self) -> Result<(ObjectRef, Op)> {

        let hex = fs::read_to_string(self.oxy.join("ops").join("head"))?;

        let r = ObjectRef::from_hex(hex.trim()).ok_or_else(|| RepoError::Msg("corrupt .oxy/ops/head".into()))?;

        let op = Op::decode(&self.store.get_typed(&r, ObjectType::Op)?)?;

        Ok((r, op))

    }

    pub fn view(&self) -> Result<View> {

        Ok(self.head_op()?.1.view)

    }

    fn record_op(&self, parents: &[ObjectRef], command: &str, view: View) -> Result<ObjectRef> {

        let op = Op { parents: parents.to_vec(), hlc: Hlc::now(), command: command.into(), view };

        let r = self.store.put(ObjectType::Op, &op.encode())?;

        write_atomic(&self.oxy.join("ops").join("head"), r.to_hex().as_bytes())?;

        Ok(r)

    }

    pub fn op_log(&self) -> Result<Vec<(ObjectRef, Op)>> {

        let mut out = Vec::new();

        let (mut r, mut op) = self.head_op()?;

        loop {

            let next = op.parents.first().copied();

            out.push((r, op));

            match next {

                Some(p) => {

                    r = p;

                    op = Op::decode(&self.store.get_typed(&r, ObjectType::Op)?)?;

                }

                None => break,

            }

        }

        Ok(out)

    }

    /// Undo the last user command (spec §12.1). Operations that only recorded

    /// a working-copy snapshot are skipped, since the files are still on disk

    /// and the next snapshot recreates them.

    pub fn undo(&self) -> Result<Op> {

        let (_, mut op) = self.head_op()?;

        while op.is_snapshot() {

            let Some(parent) = op.parents.first() else { break };

            op = Op::decode(&self.store.get_typed(parent, ObjectType::Op)?)?;

        }

        let Some(parent) = op.parents.first() else {

            return fail("nothing to undo");

        };

        let parent_op = Op::decode(&self.store.get_typed(parent, ObjectType::Op)?)?;

        write_atomic(&self.oxy.join("ops").join("head"), parent.to_hex().as_bytes())?;

        Ok(parent_op)

    }

    /// The last operation that was not a snapshot.

    pub fn last_command(&self) -> Result<Op> {

        let (_, mut op) = self.head_op()?;

        while op.is_snapshot() {

            let Some(parent) = op.parents.first() else { break };

            op = Op::decode(&self.store.get_typed(parent, ObjectType::Op)?)?;

        }

        Ok(op)

    }

    // ------------------------------------------------------------ states

    /// Load the dependency closure of `heads` from the store.

    pub fn load_state(&self, heads: &[ChangeHash]) -> Result<State> {

        let mut state = State::new();

        let mut stack: Vec<ChangeHash> = heads.to_vec();

        let mut seen: BTreeSet<ChangeHash> = BTreeSet::new();

        while let Some(h) = stack.pop() {

            if !seen.insert(h) {

                continue;

            }

            let c = self.store.get_change(&h)?;

            stack.extend(c.deps.iter().copied());

            state.add_unchecked(c);

        }

        state.validate()?;

        Ok(state)

    }

    pub fn working_copy(&self) -> Result<(ChangeHash, Change)> {

        let view = self.view()?;

        let h = *view

            .workspaces

            .get(&self.workspace)

            .ok_or_else(|| RepoError::Msg("this workspace is not in the current view".into()))?;

        Ok((h, self.store.get_change(&h)?))

    }

    /// Heads of a bookmark's state (spec §10.1).

    pub fn heads_of(&self, view: &View, bookmark: &str) -> Result<Vec<ChangeHash>> {

        match view.bookmarks.get(bookmark) {

            Some(st) => Ok(self.store.get_state(st)?.heads),

            None => Ok(vec![]),

        }

    }

    pub fn bookmark_heads(&self) -> Result<Vec<ChangeHash>> {

        self.heads_of(&self.view()?, &self.config.bookmark)

    }

    // ------------------------------------------------------------ blobs

    fn blob_for(content: &[u8]) -> Blob {

        Blob {

            length: content.len() as u64,

            chunks: crate::chunk::chunks(content).into_iter().map(|c| hash_object(ObjectType::Chunk, c)).collect(),

        }

    }

    pub fn blob_ref(content: &[u8]) -> ObjectRef {

        Self::blob_for(content).hash()

    }

    pub fn store_blob(&self, content: &[u8]) -> Result<ObjectRef> {

        for c in crate::chunk::chunks(content) {

            self.store.put_chunk(c)?;

        }

        Ok(self.store.put(ObjectType::Blob, &Self::blob_for(content).encode())?)

    }

    pub fn read_blob(&self, r: &ObjectRef) -> Result<Vec<u8>> {

        let blob = Blob::decode(&self.store.get_typed(r, ObjectType::Blob)?)?;

        let mut out = Vec::with_capacity(blob.length as usize);

        for c in &blob.chunks {

            out.extend(self.store.get_typed(c, ObjectType::Chunk)?);

        }

        Ok(out)

    }

    // ------------------------------------------------------------ working copy

    fn walk_working_copy(&self) -> Result<BTreeMap<String, FsEntry>> {

        let mut wb = ignore::WalkBuilder::new(&self.root);

        wb.hidden(false)

            .git_ignore(false)

            .git_global(false)

            .git_exclude(false)

            .require_git(false)

            .follow_links(false)