import type { ExtensionAPI, ExtensionContext } from "@earendil-works/pi-coding-agent";
import type { AutocompleteProvider, AutocompleteSuggestions } from "@earendil-works/pi-tui";
import { fileURLToPath } from "node:url";
import { resolveWorkspaceIdentity } from "./workspace.ts";

const ENTRY = "delivery-activation";
type Activation = { enabled: boolean; tools?: string[] };
type Runtime = { initialize(): Promise<void>; showStatus(ctx: ExtensionContext): Promise<boolean>; assertCanExit(ctx: ExtensionContext): Promise<void>; cleanup?(ctx: ExtensionContext): Promise<void> };

function prioritizeDeliveryShape(suggestions: AutocompleteSuggestions | null): AutocompleteSuggestions | null {
	if (!suggestions) return suggestions;
	const shapeIndex = suggestions.items.findIndex((item) => item.value === "delivery-shape");
	const firstDeliveryIndex = suggestions.items.findIndex((item) => item.value.startsWith("delivery-"));
	if (shapeIndex < 0 || firstDeliveryIndex < 0 || shapeIndex <= firstDeliveryIndex) return suggestions;
	const items = [...suggestions.items];
	const [shape] = items.splice(shapeIndex, 1);
	items.splice(firstDeliveryIndex, 0, shape!);
	return { ...suggestions, items };
}

function shapeFirstAutocomplete(current: AutocompleteProvider): AutocompleteProvider {
	return {
		triggerCharacters: current.triggerCharacters,
		getSuggestions: async (...args: Parameters<AutocompleteProvider["getSuggestions"]>) => prioritizeDeliveryShape(await current.getSuggestions(...args)),
		applyCompletion: (...args: Parameters<AutocompleteProvider["applyCompletion"]>) => current.applyCompletion(...args),
		...(current.shouldTriggerFileCompletion ? { shouldTriggerFileCompletion: (...args: Parameters<NonNullable<AutocompleteProvider["shouldTriggerFileCompletion"]>>) => current.shouldTriggerFileCompletion!(...args) } : {}),
	};
}

// 只保存用户选择的入口和原工具集合，不保存或恢复批准。
export function installActivation(pi: ExtensionAPI, start: (ctx: ExtensionContext) => Runtime): void {
	let runtime: Runtime | undefined;
	let originalTools: string[] = [];
	let restoreTools: string[] | undefined;
	let changing = false;
	let autocompleteInstalled = false;
	const enter = async (ctx: ExtensionContext) => {
		runtime ??= start(ctx);
		await runtime.initialize();
	};
	pi.on("session_start", async (event, ctx) => {
		if (ctx.hasUI && !autocompleteInstalled) {
			ctx.ui.addAutocompleteProvider(shapeFirstAutocomplete);
			autocompleteInstalled = true;
		}
		const entry = ctx.sessionManager.getEntries().findLast((row) => row.type === "custom" && row.customType === ENTRY);
		if (entry?.type !== "custom") return;
		const state = entry.data as Activation;
		if (state.enabled) {
			originalTools = state.tools ?? [];
			await enter(ctx);
			if (event.reason === "reload") ctx.ui.notify("交付扩展已重载。旧实施确认已失效；重新确认方案后再继续。需要退出时使用 /delivery-status。", "info");
		} else if (state.tools) {
			restoreTools = state.tools;
		}
	});
	// 此事件在所有 session_start 钩子之后运行，避免原插件启动时覆盖用户停用选择。
	pi.on("resources_discover", () => {
		if (!restoreTools) return;
		pi.setActiveTools(restoreTools.filter((name) => pi.getAllTools().some((tool) => tool.name === name)));
		pi.appendEntry(ENTRY, { enabled: false });
		restoreTools = undefined;
	});
	pi.registerCommand("delivery-status", {
		description: "查看交付进度和详情，结束交付",
		handler: async (_args, ctx) => {
			if (!runtime) { ctx.ui.notify("交付未启用，当前沿用 Pi 原有工具。使用 /delivery-shape 进入交付流程。", "info"); return; }
			if (!await runtime.showStatus(ctx)) return;
			if (changing || !ctx.isIdle() || ctx.hasPendingMessages()) {
				ctx.ui.notify("暂不能结束交付：仍有任务或占用未完成。先说“继续”完成恢复，或等待当前回合结束。", "warning");
				return;
			}
			changing = true;
			try { await runtime.assertCanExit(ctx); await runtime.cleanup?.(ctx); }
			catch (error) {
				changing = false;
				ctx.ui.notify(`暂不能结束交付：${String(error)}`, "warning");
				return;
			}
			pi.appendEntry(ENTRY, { enabled: false, tools: originalTools });
			pi.sendMessage({ customType: "delivery-mode", content: "用户已在状态面板中选择结束本轮受控交付。后续普通请求沿用 Pi 原有工具与项目规则，不再要求交付阶段确认；旧交付记录只供查阅，不授予新权限。", display: false }, { triggerTurn: false });
			pi.setActiveTools(originalTools);
			ctx.ui.notify("交付已结束，正在重载并恢复原工具；执行记录保留，旧批准不再有效。", "info");
			await ctx.reload();
		},
	});
	pi.registerCommand("delivery-shape", {
		description: "启用当前会话的受控交付，可附带需求",
		handler: async (args, ctx) => {
			if (changing || !ctx.isIdle() || ctx.hasPendingMessages()) {
				ctx.ui.notify("请等待当前回合和排队消息结束后再进入交付。", "warning");
				return;
			}
			changing = true;
			try {
				// 交付以 worktree 为单位记录 writer；非 Git 目录在首次批准或写入时才失败会误导用户。
				try { await resolveWorkspaceIdentity(ctx.cwd); }
				catch (error) {
					ctx.ui.notify(`交付需要 Git 仓库（writer lease 以 worktree 为单位）；当前目录未能确认 Git 工作区：${error instanceof Error ? error.message : String(error)}\n继续使用普通 Pi，未启用交付。`, "warning");
					return;
				}
				if (!runtime) {
					originalTools = pi.getActiveTools();
					pi.appendEntry(ENTRY, { enabled: true, tools: originalTools });
					await enter(ctx);
				}
				ctx.ui.notify("交付已启用。确认方案后会自动实施；中断后直接说“继续”。需要退出时使用 /delivery-status。", "info");
				if (args.trim()) pi.sendUserMessage(`先读取并遵循 ${fileURLToPath(new URL("../../../skills/adaptive-delivery/SKILL.md", import.meta.url))}，核实项目事实并对齐需求；明确需求可以零追问，简单任务无须规划文档。当前需求：\n${args}`, { expandPromptTemplates: false });
			} finally { changing = false; }
		},
	});
}