import type { ExtensionAPI } from "@earendil-works/pi-coding-agent";
import { Key, matchesKey } from "@earendil-works/pi-tui";
import { SplitDialog } from "./dialog.js";
import { exportStatsCsv } from "./export.js";
import { renderGraphView } from "./graph-view.js";
import { renderMissesView } from "./misses-view.js";
import { collectCacheSessionMetrics } from "./session-data.js";
import { renderStatsView } from "./stats-view.js";
import { buildSummaryLines } from "./summary.js";

type CacheView = "distribution" | "misses" | "stats";

const VIEW_LABELS: Record<CacheView, string> = {
  distribution: "Turn distribution",
  misses: "Miss analysis",
  stats: "Per-message table",
};

const VIEW_ORDER: CacheView[] = ["stats", "distribution", "misses"];

function initialViewFromArgs(args: string): CacheView {
  const sub = args.trim().toLowerCase();
  if (sub === "graph") return "distribution";
  return "stats"; // default: per-message table
}

export default function cacheInsightExtension(pi: ExtensionAPI): void {
  pi.registerCommand("cache", {
    description: "Session cache-prefix analysis: summary, turn distribution, miss analysis, or CSV export",
    getArgumentCompletions(prefix) {
      const items = [
        { value: "graph", label: "graph", description: "Open cache viewer (turn-distribution chart)" },
        { value: "export", label: "export", description: "Export stats data to a CSV in the OS temp dir" },
      ];

      const filtered = items.filter((item) => item.value.startsWith(prefix.toLowerCase()));
      return filtered.length > 0 ? filtered : items;
    },
    handler: async (args, ctx) => {
      const sub = args.trim().toLowerCase();

      if (sub === "export") {
        const metrics = collectCacheSessionMetrics(ctx.sessionManager, ctx.modelRegistry);
        const filePath = await exportStatsCsv(ctx.sessionManager, metrics);
        ctx.ui.notify(`Exported cache stats CSV to ${filePath}`, "info");
        return;
      }

      if (!ctx.hasUI) {
        ctx.ui.notify(
          "/cache requires interactive TUI mode. Use /cache export in non-interactive mode.",
          "info",
        );
        return;
      }

      let currentView: CacheView = initialViewFromArgs(args);
      const metrics = collectCacheSessionMetrics(ctx.sessionManager, ctx.modelRegistry);

      // Render in the editor slot (same mechanism as /model's selector panel):
      // the dialog appears right where the input box is, growing upward, so
      // it stays inside the user's visual focus area instead of floating
      // mid-screen as an overlay.
      await ctx.ui.custom<void>(
        (_tui, theme, _keybindings, done) =>
          new SplitDialog(
            theme,
            {
              title: "Cache Insight",
              getTitle: () => `Cache Insight — ${VIEW_LABELS[currentView]}`,
              helpText: "{Tab} cycle view • {j}/{k} scroll • {q} close",
              renderHeader: () => buildSummaryLines(theme, metrics, ctx.getContextUsage()),
              renderBody: (innerWidth) => {
                if (currentView === "stats") return renderStatsView(theme, metrics.allMessages, innerWidth);
                if (currentView === "misses") return renderMissesView(theme, metrics.allMessages, innerWidth);
                return renderGraphView(theme, metrics.allMessages, innerWidth);
              },
              onKey: (data) => {
                if (matchesKey(data, Key.tab)) {
                  const idx = VIEW_ORDER.indexOf(currentView);
                  currentView = VIEW_ORDER[(idx + 1) % VIEW_ORDER.length]!;
                  return true;
                }
                return false;
              },
            },
            () => done(undefined),
          ),
      );
    },
  });
}