import { basename } from "node:path";
import type { StopReason } from "@earendil-works/pi-ai";
import {
  type ExtensionAPI,
  type ExtensionContext,
} from "@earendil-works/pi-coding-agent";
import { errorMessage } from "./errors.ts";
import { safeTerminalText } from "./safe-terminal-text.ts";
import { createKillerosSettingsStore } from "./settings.ts";

export interface NotificationPreferenceStore {
  load(): boolean;
  save(enabled: boolean): void;
}

export interface CompletionNotificationDependencies {
  store: NotificationPreferenceStore;
  ring(): void;
}

export const COMPLETION_BELL_GLYPH = "󰂚";

export function createNotificationPreferenceStore(
  settingsPath?: string,
): NotificationPreferenceStore {
  const settings = createKillerosSettingsStore(settingsPath);
  return {
    load: () => settings.load().completionSound === true,
    save: (enabled) => {
      settings.update({ completionSound: enabled });
    },
  };
}

export function formatNotificationTitle(
  cwd: string,
  sessionName: string | undefined,
  enabled: boolean,
): string {
  const directory = basename(cwd) || cwd;
  const base = sessionName ? `π - ${sessionName} - ${directory}` : `π - ${directory}`;
  return safeTerminalText(enabled ? `${base} ${COMPLETION_BELL_GLYPH}` : base).replaceAll("\n", "");
}

export function registerCompletionNotifications(
  pi: ExtensionAPI,
  dependencies?: CompletionNotificationDependencies,
): void {
  const runtime = dependencies ?? {
    store: createNotificationPreferenceStore(),
    ring: () => { process.stdout.write("\x07"); },
  };
  let enabled = false;
  let requestPending = false;
  let lastStopReason: StopReason | undefined;

  const applyTitle = (ctx: ExtensionContext): void => {
    if (ctx.mode !== "tui") return;
    ctx.ui.setTitle(formatNotificationTitle(ctx.cwd, pi.getSessionName(), enabled));
  };

  pi.registerCommand("notification", {
    description: "Configure the completion sound",
    handler: async (_args, ctx) => {
      if (ctx.mode !== "tui") {
        ctx.ui.notify("/notification requires TUI mode", "error");
        return;
      }
      const selected = await ctx.ui.select("Completion sound", [
        enabled ? "On ← current" : "On",
        enabled ? "Off" : "Off ← current",
      ]);
      if (!selected) return;
      const nextEnabled = selected.startsWith("On");
      try {
        runtime.store.save(nextEnabled);
      } catch (error) {
        ctx.ui.notify(`Completion sound setting could not be saved: ${errorMessage(error)}`, "error");
        return;
      }
      enabled = nextEnabled;
      applyTitle(ctx);
      ctx.ui.notify(`Completion sound: ${enabled ? "On" : "Off"}`, "info");
    },
  });

  pi.on("session_start", (_event, ctx) => {
    requestPending = false;
    lastStopReason = undefined;
    if (ctx.mode !== "tui") return;
    try {
      enabled = runtime.store.load();
    } catch (error) {
      enabled = false;
      ctx.ui.notify(`Completion sound settings could not be read: ${errorMessage(error)}`, "error");
    }
    applyTitle(ctx);
  });

  pi.on("session_info_changed", (_event, ctx) => applyTitle(ctx));

  pi.on("agent_start", (_event, ctx) => {
    if (ctx.mode !== "tui") return;
    requestPending = true;
    lastStopReason = undefined;
  });

  pi.on("agent_end", (event, ctx) => {
    if (ctx.mode !== "tui" || !requestPending) return;
    lastStopReason = undefined;
    for (let index = event.messages.length - 1; index >= 0; index -= 1) {
      const message = event.messages[index];
      if (message?.role !== "assistant") continue;
      lastStopReason = message.stopReason;
      break;
    }
  });

  pi.on("agent_settled", (_event, ctx) => {
    if (ctx.mode !== "tui" || !requestPending) return;
    if (!ctx.isIdle() || ctx.hasPendingMessages()) return;
    requestPending = false;
    if (!enabled || lastStopReason === "aborted") return;
    try {
      runtime.ring();
    } catch (error) {
      ctx.ui.notify(`Completion sound failed: ${errorMessage(error)}`, "error");
    }
  });

  pi.on("session_shutdown", () => {
    requestPending = false;
    lastStopReason = undefined;
  });
}