// =====================================================================
// cleanup.sx — `dist store cleanup`: retention pruning + store garbage
// collection over the persisted store (subplan 02, Slice 4).
//
// One pass, four deletions, all audited:
//
//   1. RELEASES beyond retention. For every channel with
//      `retention_keep` = N > 0, the channel's lineage (the app's
//      PUBLISHED releases targeting that channel, in publish order)
//      keeps its newest N entries; older ones are deleted — UNLESS a
//      release is currently pointed at by ANY channel (cross-promotion
//      means e.g. stable may point into beta's lineage), in which case
//      it survives and is reported in `kept_pointed_releases`.
//   2. ARTIFACT rows of the deleted releases.
//   3. OBJECT files in `<store>/objects/` that no surviving artifact
//      references (covers both blobs freed by 1/2 and blobs orphaned by
//      an aborted upload that never reached a release).
//   4. EVERYTHING in `<store>/staging/`. A completed put always renames
//      or deletes its staging file, so anything still there is a
//      leftover from a crashed/aborted publish.
//
// ORDERING: the pruned model (with one audit event per deletion) is
// saved to dist.db BEFORE any file is unlinked, so a crash mid-cleanup
// can leave an unreferenced blob (the next run catches it) but never a
// model row pointing at deleted bytes. An unlink that fails after the
// save is reported in `unlink_failed` (exit stays 0 — the model is
// consistent; the orphan is re-detected next run).
//
// OFFLINE OP: like every load-modify-save CLI command, cleanup must not
// run concurrently with a writing distd — the whole-model save would
// drop a publish that landed in between, and the staging sweep would
// eat an in-flight upload's temp file.
// =====================================================================

#import "modules/std.sx";
#import "modules/std/json.sx";
fs :: #import "modules/std/fs.sx";
#import "../domain/platform.sx";
#import "../domain/app.sx";
#import "../domain/release.sx";
#import "../domain/artifact.sx";
#import "../domain/channel.sx";
#import "../domain/token.sx";
#import "../domain/audit.sx";
#import "../domain/validate.sx";
#import "../repo/repo.sx";
db   :: #import "../repo/db.sx";
jout :: #import "../json_out.sx";
pl   :: #import "../publish/publish.sx";

CleanupErr :: error {
    Load,       // store database absent or unreadable
    Persist,    // the pruned model could not be re-written
}

CleanupOutcome :: struct {
    releases_deleted: List(string);        // release ids pruned by retention
    objects_deleted: List(string);         // storage keys no longer referenced
    staging_deleted: List(string);         // staging file names swept
    kept_pointed_releases: List(string);   // beyond retention but channel-pointed
    unlink_failed: List(string);           // paths whose unlink failed post-save
}

// ── directory listing (no std.fs equivalent yet) ─────────────────────
// opendir/readdir/closedir via libc, like publish.sx's time(2) shim.
// dirent layout is darwin-arm64: d_type at byte 20, d_name
// (NUL-terminated, max 1024) at byte 21.

cl_libc     :: #library "c";
cl_opendir  :: (path: [:0]u8) -> usize #foreign cl_libc "opendir";
cl_readdir  :: (dirp: usize) -> usize #foreign cl_libc "readdir";
cl_closedir :: (dirp: usize) -> i32 #foreign cl_libc "closedir";

CL_DT_REG :: 8;

// Regular-file names in `dir` (no recursion), copied into the context
// allocator (the dirent buffer is libc-owned and dies on the next read).
// A missing/unopenable directory lists as empty: a store without
// objects/ or staging/ simply has nothing to delete.
cl_list_files :: (dir: string) -> List(string) {
    names : List(string) = .{};
    dp := cl_opendir(dir);
    if dp == 0 { return names; }
    while true {
        ent := cl_readdir(dp);
        if ent == 0 { break; }
        p : [*]u8 = xx ent;
        if p[20] == CL_DT_REG {
            n := 0;
            while p[21 + n] != 0 and n < 1023 { n += 1; }
            view := string.{ ptr = @p[21], len = n };
            names.append(db.db_dup_str(view, context.allocator), context.allocator);
        }
    }
    cl_closedir(dp);
    return names;
}

cl_contains :: (l: *List(string), s: string) -> bool {
    i := 0;
    while i < l.len {
        if l.items[i] == s { return true; }
        i += 1;
    }
    return false;
}

// ── the cleanup transaction ──────────────────────────────────────────

run_cleanup :: (store_dir: string, fail_out: *jout.CliFailure) -> (CleanupOutcome, !CleanupErr) {
    if !db.store_exists(store_dir) {
        fail_out.code    = "store.load";
        fail_out.message = concat("no store database (nothing published yet): ", store_dir);
        raise error.Load;
    }
    repo, le := db.load(store_dir);
    if le {
        fail_out.code    = "store.load";
        fail_out.message = concat("the store database could not be loaded: ", store_dir);
        raise error.Load;
    }

    alloc := context.allocator;
    o : CleanupOutcome = .{};

    // Every channel's current pointer is sacrosanct, whichever channel's
    // lineage the release came from.
    guard : List(string) = .{};
    i := 0;
    while i < repo.channels.len {
        cur := repo.channels.items[i].current_release_id;
        if cur.len > 0 { guard.append(cur, alloc); }
        i += 1;
    }

    // Per retention-bearing channel: the lineage's oldest entries beyond
    // `retention_keep` are pruned (or spared by the pointer guard). A
    // release targets exactly one channel, so lineages never overlap.
    i = 0;
    while i < repo.channels.len {
        chan := repo.channels.items[i];
        i += 1;
        if chan.retention_keep <= 0 { continue; }

        total := 0;
        j := 0;
        while j < repo.releases.len {
            r := repo.releases.items[j];
            if r.app_id == chan.app_id and r.channel == chan.name and r.published_at > 0 { total += 1; }
            j += 1;
        }
        if total <= chan.retention_keep { continue; }

        drop := total - chan.retention_keep;   // oldest `drop` lineage entries
        seen := 0;
        j = 0;
        while j < repo.releases.len and seen < drop {
            r := repo.releases.items[j];
            j += 1;
            if !(r.app_id == chan.app_id and r.channel == chan.name and r.published_at > 0) { continue; }
            seen += 1;
            if cl_contains(@guard, r.id) {
                o.kept_pointed_releases.append(r.id, alloc);
            } else {
                o.releases_deleted.append(r.id, alloc);
            }
        }
    }

    // Storage keys the surviving artifacts still reference; any objects/
    // file outside this set is garbage.
    referenced : List(string) = .{};
    i = 0;
    while i < repo.artifacts.len {
        a := repo.artifacts.items[i];
        if !cl_contains(@o.releases_deleted, a.release_id) {
            referenced.append(a.storage_key, alloc);
        }
        i += 1;
    }
    objects := cl_list_files(path_join(store_dir, "objects"));
    i = 0;
    while i < objects.len {
        if !cl_contains(@referenced, objects.items[i]) {
            o.objects_deleted.append(objects.items[i], alloc);
        }
        i += 1;
    }

    o.staging_deleted = cl_list_files(path_join(store_dir, "staging"));

    // Compact the model in place (order preserved): pruned releases go,
    // and their artifact rows with them.
    w := 0;
    i = 0;
    while i < repo.releases.len {
        if !cl_contains(@o.releases_deleted, repo.releases.items[i].id) {
            repo.releases.items[w] = repo.releases.items[i];
            w += 1;
        }
        i += 1;
    }
    repo.releases.len = w;
    w = 0;
    i = 0;
    while i < repo.artifacts.len {
        if !cl_contains(@o.releases_deleted, repo.artifacts.items[i].release_id) {
            repo.artifacts.items[w] = repo.artifacts.items[i];
            w += 1;
        }
        i += 1;
    }
    repo.artifacts.len = w;

    // One audit event per deletion, written into the same save.
    now := pl.now_secs();
    i = 0;
    while i < o.releases_deleted.len {
        id := o.releases_deleted.items[i];
        repo.create_audit_event(AuditEvent.{
            id = concat("evt-cleanup-release-", id),
            actor = "cli", action = "release.delete", target_type = "release",
            target_id = id, metadata = "retention", created_at = now,
        });
        i += 1;
    }
    i = 0;
    while i < o.objects_deleted.len {
        key := o.objects_deleted.items[i];
        repo.create_audit_event(AuditEvent.{
            id = concat("evt-cleanup-object-", key),
            actor = "cli", action = "object.delete", target_type = "object",
            target_id = key, metadata = "unreferenced", created_at = now,
        });
        i += 1;
    }
    i = 0;
    while i < o.staging_deleted.len {
        name := o.staging_deleted.items[i];
        repo.create_audit_event(AuditEvent.{
            id = concat("evt-cleanup-staging-", name),
            actor = "cli", action = "staging.delete", target_type = "staging",
            target_id = name, metadata = "stale", created_at = now,
        });
        i += 1;
    }

    werr := false;
    db.save(@repo, store_dir) catch { werr = true; };
    if werr {
        fail_out.code    = "persist.save";
        fail_out.message = concat("the store database could not be written: ", store_dir);
        raise error.Persist;
    }

    // Files go only after the model committed.
    i = 0;
    while i < o.objects_deleted.len {
        p := path_join(path_join(store_dir, "objects"), o.objects_deleted.items[i]);
        if !fs.delete_file(p) { o.unlink_failed.append(p, alloc); }
        i += 1;
    }
    i = 0;
    while i < o.staging_deleted.len {
        p := path_join(path_join(store_dir, "staging"), o.staging_deleted.items[i]);
        if !fs.delete_file(p) { o.unlink_failed.append(p, alloc); }
        i += 1;
    }

    return o;
}

// ── rendering ─────────────────────────────────────────────────────────

cl_str_array :: (l: *List(string), alloc: Allocator) -> Value {
    arr : Array = .{};
    i := 0;
    while i < l.len {
        arr.add(.str(l.items[i]), alloc);
        i += 1;
    }
    return .array(arr);
}

// `{"status":"cleaned","releases_deleted":[...],"objects_deleted":[...],
// "staging_deleted":[...],"kept_pointed_releases":[...],
// "unlink_failed":[...]}`.
write_cleanup_json :: (o: *CleanupOutcome, dst: []u8) -> (i64, !JsonError) {
    gpa := GPA.init();
    root : Object = .{};
    root.put("status", .str("cleaned"), xx gpa);
    root.put("releases_deleted", cl_str_array(@o.releases_deleted, xx gpa), xx gpa);
    root.put("objects_deleted", cl_str_array(@o.objects_deleted, xx gpa), xx gpa);
    root.put("staging_deleted", cl_str_array(@o.staging_deleted, xx gpa), xx gpa);
    root.put("kept_pointed_releases", cl_str_array(@o.kept_pointed_releases, xx gpa), xx gpa);
    root.put("unlink_failed", cl_str_array(@o.unlink_failed, xx gpa), xx gpa);
    rootv : Value = .object(root);
    n := try write_to_buffer(rootv, dst);
    return n;
}

cleanup_human :: (o: *CleanupOutcome) -> string {
    s := concat("cleaned: ", int_to_string(o.releases_deleted.len));
    s = concat(s, concat(" releases, ", int_to_string(o.objects_deleted.len)));
    s = concat(s, concat(" objects, ", int_to_string(o.staging_deleted.len)));
    s = concat(s, " staged files deleted");
    if o.kept_pointed_releases.len > 0 {
        s = concat(s, concat("; kept (channel-pointed): ", int_to_string(o.kept_pointed_releases.len)));
    }
    if o.unlink_failed.len > 0 {
        s = concat(s, concat("; UNLINK FAILED: ", int_to_string(o.unlink_failed.len)));
    }
    return concat(s, "\n");
}