using Invercargill;
using Invercargill.DataStructures;
using Invercargill.Expressions;
using InvercargillSql.Orm;
using Inversion;
using ClankerSaddle.Data;

namespace ClankerSaddle.Services {

    /** One materialised cross-task timeline event (plan 10 phase 3). */
    public class TimelineEvent : Object {
        /** created | started | suspended | completed | failed |
         *  block-raised | block-answered | comment | progress | dispatch |
         *  verdict | plan-submitted | force-wake | cancel | answer |
         *  goal-<kind> (plan 12) */
        public string kind { get; set; default = ""; }
        /** The event's epoch second — the newest-first sort key. */
        public int64 at_epoch { get; set; }
        public int64 task_id { get; set; }
        public string task_title { get; set; default = ""; }
        /** Plan 12: set on goal events (else 0) — the timeline links the goal. */
        public int64 goal_id { get; set; }
        public string goal_title { get; set; default = ""; }
        public string text { get; set; default = ""; }
        /** Build-order tiebreak for same-second events. */
        public int64 sequence { get; set; }
    }

    /**
     * The home dashboard's cross-task activity timeline: the last
     * {@link WINDOW} ledger events, newest first (plan 17: a pure
     * projection of the unified `events` table — the per-source table
     * scans it replaced are gone). The agent's protocol noise
     * (turn_text/tool_call/tool_result/command_output/usage) stays out;
     * everything human-relevant — status changes, block raises and
     * answers, verdicts, comments, progress, dispatches, goal
     * lifecycle — flows through.
     */
    public class TimelineService : Object {

        /** The dashboard timeline window (events shown, newest first). */
        public const int WINDOW = 50;

        /** Snippet clamp for bodies, questions and summaries. */
        public const int SNIPPET_MAX = 160;

        private OrmSession db = inject<OrmSession>();

        /**
         * The recent event window, newest first: the newest WINDOW
         * non-noise ledger rows, mapped onto the timeline's shape with
         * goal-run task rows staying internal (the goal-keyed events
         * carry the story).
         */
        public async Vector<TimelineEvent> recent_window() throws Error {
            var titles = new Dictionary<string, string>();
            var run_tasks = new Invercargill.DataStructures.HashSet<string>();
            foreach (var task in yield db.query<TaskEntity>().materialise_async()) {
                titles.set(task.id.to_string(), task.title);
                if (task.kind == TASK_KIND_GOAL_RUN) {
                    run_tasks.add(task.id.to_string());
                }
            }
            var goal_titles = new Dictionary<string, string>();
            foreach (var goal in yield db.query<Goal>().materialise_async()) {
                goal_titles.set(goal.id.to_string(), goal.title);
            }

            var rows = new Vector<EventRecord>();
            foreach (var record in yield db.query<EventRecord>()
                    .order_by_desc(expr("id")).limit(WINDOW).materialise_async()) {
                rows.add(record);
            }
            var ordered = rows.to_array();
            for (var i = 1; i < ordered.length; i++) {
                var key = ordered[i];
                var j = i - 1;
                while (j >= 0
                        && (epoch_of(ordered[j]) < epoch_of(key)
                            || (epoch_of(ordered[j]) == epoch_of(key)
                                && ordered[j].id < key.id))) {
                    ordered[j + 1] = ordered[j];
                    j--;
                }
                ordered[j + 1] = key;
            }
            var events = new Vector<TimelineEvent>();
            int64 sequence = 0;
            foreach (var record in ordered) {
                if (record.kind == EVENT_TURN_TEXT || record.kind == EVENT_TOOL_CALL
                        || record.kind == EVENT_TOOL_RESULT
                        || record.kind == EVENT_COMMAND_OUTPUT
                        || record.kind == EVENT_USAGE) {
                    continue;
                }
                bool goal_scoped = record.scope_type == EVENT_SCOPE_GOAL;
                bool task_scoped = record.scope_type == EVENT_SCOPE_TASK;
                if (task_scoped && run_tasks.has(record.scope_id.to_string())) {
                    continue;
                }
                var view = project(record);
                if (view == null) {
                    continue;
                }
                ((!)view).sequence = sequence++;
                if (goal_scoped) {
                    ((!)view).goal_id = record.scope_id;
                    ((!)view).goal_title = goal_titles.get_or_default(
                        record.scope_id.to_string()) ?? "";
                    ((!)view).kind = @"goal-$(((!)view).kind)";
                } else if (task_scoped) {
                    ((!)view).task_id = record.scope_id;
                    ((!)view).task_title = titles.get_or_default(
                        record.scope_id.to_string()) ?? "";
                }
                events.add((!)view);
            }
            return events;
        }

        /**
         * One ledger row onto the timeline shape: `kind` keeps the
         * historical vocabulary the dashboard badges (state_change's
         * `to` maps to created/started/completed/&c.), `text` prefers
         * the payload's human-readable line and falls back to a
         * per-kind synthesis. Null when the row says nothing worth a
         * timeline entry.
         */
        private static TimelineEvent? project(EventRecord record) {
            var payload = EventService.payload_of(record);
            string text = EntryJson.string_member(payload, "text");
            switch (record.kind) {
                case EVENT_STATE_CHANGE:
                    string to = EntryJson.string_member(payload, "to");
                    string kind = timeline_kind_of_status(to);
                    if (text.length == 0) {
                        text = @"Status → $(to)";
                    }
                    // Terminal transitions append the summary's first
                    // line (the old timeline snippet behaviour).
                    string summary = EntryJson.string_member(payload, "summary");
                    if (summary.length > 0 && (to == STATUS_DONE || to == STATUS_FAILED)) {
                        text = @"$(text): $(first_line(summary))";
                    }
                    return new TimelineEvent() {
                        kind = kind, at_epoch = record.created_at != null
                            ? ((!)record.created_at).to_unix() : 0,
                        text = snippet(text)
                    };
                case EVENT_ANSWER:
                    return new TimelineEvent() {
                        kind = "block-answered", at_epoch = epoch_of(record),
                        text = snippet(text.length > 0 ? text : "block answered")
                    };
                case EVENT_COMMENT:
                    string author = EntryJson.string_member(payload, "author");
                    string body = EntryJson.string_member(payload, "body");
                    if (author == COMMENT_AUTHOR_SYSTEM && comment_is_mechanical(body)) {
                        return null;
                    }
                    return new TimelineEvent() {
                        kind = "comment", at_epoch = epoch_of(record),
                        text = snippet(@"$(author): $(body)")
                    };
                case EVENT_PROGRESS:
                    return new TimelineEvent() {
                        kind = "progress", at_epoch = epoch_of(record),
                        text = snippet(EntryJson.string_member(payload, "text"))
                    };
                case EVENT_LIFECYCLE:
                    return new TimelineEvent() {
                        kind = "dispatch", at_epoch = epoch_of(record),
                        text = snippet(text.length > 0 ? text : "dispatched")
                    };
                case EVENT_VERDICT:
                    return new TimelineEvent() {
                        kind = "verdict", at_epoch = epoch_of(record),
                        text = snippet(text.length > 0 ? text : "verdict")
                    };
                case EVENT_PLAN_SUBMITTED:
                    return new TimelineEvent() {
                        kind = "plan-submitted", at_epoch = epoch_of(record),
                        text = snippet(text.length > 0 ? text : "plan submitted for review")
                    };
                case EVENT_FORCE_WAKE:
                    return new TimelineEvent() {
                        kind = "force-wake", at_epoch = epoch_of(record),
                        text = snippet(text.length > 0 ? text : "force-woke")
                    };
                case EVENT_CANCEL:
                    return new TimelineEvent() {
                        kind = "cancel", at_epoch = epoch_of(record),
                        text = snippet(text.length > 0 ? text : "cancelled")
                    };
                default:
                    return null;
            }
        }

        /** A terminal `to` status onto the timeline's historical kind. */
        private static string timeline_kind_of_status(string to) {
            switch (to) {
                case STATUS_DRAFT:
                    return "created";
                case STATUS_WORKING:
                case STATUS_ASSIGNED:
                    return "started";
                case STATUS_SUSPENDED:
                    return "suspended";
                case STATUS_DONE:
                    return "completed";
                case STATUS_FAILED:
                    return "failed";
                case STATUS_BLOCKED:
                case STATUS_REVIEW_REQUESTED:
                    return "block-raised";
                default:
                    return to.length > 0 ? to : "state";
            }
        }

        private static int64 epoch_of(EventRecord record) {
            return record.created_at != null ? ((!)record.created_at).to_unix() : 0;
        }

        private static string first_line(string body) {
            int cut = body.index_of_char('\n');
            return cut >= 0 ? body.substring(0, cut) : body;
        }

        private static string snippet(string body) {
            string flat = body.replace("\n", " ");
            return flat.length > SNIPPET_MAX ? flat.substring(0, SNIPPET_MAX) + "…" : flat;
        }
    }
}