#!/usr/bin/env bun
/**
 * gstack-decision-search — read active decisions (the curated "what did we decide" view).
 *
 * Usage:
 *   gstack-decision-search [--query KW] [--scope repo|branch|issue]
 *                          [--branch B] [--issue I] [--recent N] [--all] [--json]
 *
 * Reads the BOUNDED active snapshot (decisions.active.json) — O(active), not a full
 * history scan — and rebuilds it from the event log if missing. Scope-filtered to the
 * current branch/issue context (recency != relevance). NON-INTERACTIVE. `--all` shows
 * superseded decisions too (from the full log). Exit 0 silently when there are none.
 */

import { existsSync } from "fs";
import { spawnSync } from "child_process";
import {
  decisionPaths,
  readSnapshot,
  rebuildSnapshot,
  readEvents,
  filterByScope,
  type ActiveDecision,
} from "../lib/gstack-decision";

const HERE = import.meta.dir;
const args = process.argv.slice(2);

function resolveSlug(): string {
  const r = spawnSync(`${HERE}/gstack-slug`, { encoding: "utf-8" });
  const m = (r.stdout || "").match(/^SLUG=(.+)$/m);
  return m ? m[1].trim() : "unknown";
}
function gitBranch(): string | undefined {
  const r = spawnSync("git", ["rev-parse", "--abbrev-ref", "HEAD"], { encoding: "utf-8" });
  const b = (r.stdout || "").trim();
  return b && b !== "HEAD" ? b : undefined;
}
function flagValue(name: string): string | undefined {
  const i = args.indexOf(name);
  return i >= 0 ? args[i + 1] : undefined;
}

const slug = resolveSlug();
const paths = decisionPaths(slug);
const query = flagValue("--query")?.toLowerCase();
const scope = flagValue("--scope");
const branch = flagValue("--branch") ?? gitBranch();
const issue = flagValue("--issue");
const recent = flagValue("--recent") ? parseInt(flagValue("--recent") as string, 10) : undefined;
const showAll = args.includes("--all");
const asJson = args.includes("--json");

let rows: ActiveDecision[];
if (showAll) {
  // include superseded: every decide event from the full log (no active filter)
  rows = readEvents(paths).filter((e): e is ActiveDecision => e.kind === "decide");
} else {
  rows = readSnapshot(paths);
  // Rebuild only when a snapshot is absent but a log exists (don't write a snapshot
  // into a nonexistent store on an empty read — just return nothing).
  if (!rows.length && existsSync(paths.log)) rows = rebuildSnapshot(paths);
}

rows = filterByScope(rows, { branch, issue });
if (scope) rows = rows.filter((d) => d.scope === scope);
if (query) {
  rows = rows.filter((d) =>
    [d.decision, d.rationale, d.alternatives_considered]
      .filter((s): s is string => typeof s === "string")
      .some((s) => s.toLowerCase().includes(query)),
  );
}
rows.sort((a, b) => (a.date < b.date ? 1 : a.date > b.date ? -1 : 0)); // newest first
if (recent && recent > 0) rows = rows.slice(0, recent);

if (asJson) {
  console.log(JSON.stringify(rows));
  process.exit(0);
}
if (!rows.length) process.exit(0); // silent when nothing relevant

for (const d of rows) {
  const scopeTag = d.scope === "repo" ? "" : ` [${d.scope}${d.branch ? `:${d.branch}` : ""}${d.issue ? `:${d.issue}` : ""}]`;
  console.log(`- ${d.decision}${scopeTag} (${d.source}, ${d.date.slice(0, 10)})`);
  if (d.rationale) console.log(`  why: ${d.rationale}`);
}