/**
 * Plan Mode Hook
 *
 * Provides a Claude Code-style "plan mode" for safe code exploration.
 * When enabled, the agent can only use read-only tools and cannot modify files.
 *
 * Features:
 * - /plan command to toggle plan mode
 * - In plan mode: only read, bash (read-only), grep, find, ls are available
 * - Injects system context telling the agent about the restrictions
 * - After each agent response, prompts to execute the plan or continue planning
 * - Shows "plan" indicator in footer when active
 * - Extracts todo list from plan and tracks progress during execution
 * - Agent marks steps complete by outputting [DONE:id] tags
 *
 * Usage:
 * 1. Copy this file to ~/.pi/agent/hooks/ or your project's .pi/hooks/
 * 2. Use /plan to toggle plan mode on/off
 * 3. Or start in plan mode with --plan flag
 */

import type { HookAPI, HookContext } from "@mariozechner/pi-coding-agent/hooks";

// Read-only tools for plan mode
const PLAN_MODE_TOOLS = ["read", "bash", "grep", "find", "ls"];

// Full set of tools for normal mode
const NORMAL_MODE_TOOLS = ["read", "bash", "edit", "write"];

// Patterns for destructive bash commands that should be blocked in plan mode
const DESTRUCTIVE_PATTERNS = [
	/\brm\b/i,
	/\brmdir\b/i,
	/\bmv\b/i,
	/\bcp\b/i,
	/\bmkdir\b/i,
	/\btouch\b/i,
	/\bchmod\b/i,
	/\bchown\b/i,
	/\bchgrp\b/i,
	/\bln\b/i,
	/\btee\b/i,
	/\btruncate\b/i,
	/\bdd\b/i,
	/\bshred\b/i,
	/[^<]>(?!>)/,
	/>>/,
	/\bnpm\s+(install|uninstall|update|ci|link|publish)/i,
	/\byarn\s+(add|remove|install|publish)/i,
	/\bpnpm\s+(add|remove|install|publish)/i,
	/\bpip\s+(install|uninstall)/i,
	/\bapt(-get)?\s+(install|remove|purge|update|upgrade)/i,
	/\bbrew\s+(install|uninstall|upgrade)/i,
	/\bgit\s+(add|commit|push|pull|merge|rebase|reset|checkout\s+-b|branch\s+-[dD]|stash|cherry-pick|revert|tag|init|clone)/i,
	/\bsudo\b/i,
	/\bsu\b/i,
	/\bkill\b/i,
	/\bpkill\b/i,
	/\bkillall\b/i,
	/\breboot\b/i,
	/\bshutdown\b/i,
	/\bsystemctl\s+(start|stop|restart|enable|disable)/i,
	/\bservice\s+\S+\s+(start|stop|restart)/i,
	/\b(vim?|nano|emacs|code|subl)\b/i,
];

// Read-only commands that are always safe
const SAFE_COMMANDS = [
	/^\s*cat\b/,
	/^\s*head\b/,
	/^\s*tail\b/,
	/^\s*less\b/,
	/^\s*more\b/,
	/^\s*grep\b/,
	/^\s*find\b/,
	/^\s*ls\b/,
	/^\s*pwd\b/,
	/^\s*echo\b/,
	/^\s*printf\b/,
	/^\s*wc\b/,
	/^\s*sort\b/,
	/^\s*uniq\b/,
	/^\s*diff\b/,
	/^\s*file\b/,
	/^\s*stat\b/,
	/^\s*du\b/,
	/^\s*df\b/,
	/^\s*tree\b/,
	/^\s*which\b/,
	/^\s*whereis\b/,
	/^\s*type\b/,
	/^\s*env\b/,
	/^\s*printenv\b/,
	/^\s*uname\b/,
	/^\s*whoami\b/,
	/^\s*id\b/,
	/^\s*date\b/,
	/^\s*cal\b/,
	/^\s*uptime\b/,
	/^\s*ps\b/,
	/^\s*top\b/,
	/^\s*htop\b/,
	/^\s*free\b/,
	/^\s*git\s+(status|log|diff|show|branch|remote|config\s+--get)/i,
	/^\s*git\s+ls-/i,
	/^\s*npm\s+(list|ls|view|info|search|outdated|audit)/i,
	/^\s*yarn\s+(list|info|why|audit)/i,
	/^\s*node\s+--version/i,
	/^\s*python\s+--version/i,
	/^\s*curl\s/i,
	/^\s*wget\s+-O\s*-/i,
	/^\s*jq\b/,
	/^\s*sed\s+-n/i,
	/^\s*awk\b/,
	/^\s*rg\b/,
	/^\s*fd\b/,
	/^\s*bat\b/,
	/^\s*exa\b/,
];

function isSafeCommand(command: string): boolean {
	if (SAFE_COMMANDS.some((pattern) => pattern.test(command))) {
		if (!DESTRUCTIVE_PATTERNS.some((pattern) => pattern.test(command))) {
			return true;
		}
	}
	if (DESTRUCTIVE_PATTERNS.some((pattern) => pattern.test(command))) {
		return false;
	}
	return true;
}

// Todo item with unique ID
interface TodoItem {
	id: string;
	text: string;
	completed: boolean;
}

// Generate a short unique ID
function generateId(): string {
	return Math.random().toString(36).substring(2, 8);
}

/**
 * Extract todo items from assistant message and assign IDs.
 */
function extractTodoItems(message: string): TodoItem[] {
	const items: TodoItem[] = [];

	// Match numbered lists: "1. Task" or "1) Task"
	const numberedPattern = /^\s*(\d+)[.)]\s+\*{0,2}([^*\n]+)/gm;
	for (const match of message.matchAll(numberedPattern)) {
		let text = match[2].trim();
		text = text.replace(/\*{1,2}$/, "").trim();
		if (text.length > 5 && !text.startsWith("`") && !text.startsWith("/") && !text.startsWith("-")) {
			items.push({ id: generateId(), text, completed: false });
		}
	}

	// If no numbered items, try bullet points
	if (items.length === 0) {
		const stepPattern = /^\s*[-*]\s*(?:Step\s*\d+[:.])?\s*\*{0,2}([^*\n]+)/gim;
		for (const match of message.matchAll(stepPattern)) {
			let text = match[1].trim();
			text = text.replace(/\*{1,2}$/, "").trim();
			if (text.length > 10 && !text.startsWith("`")) {
				items.push({ id: generateId(), text, completed: false });
			}
		}
	}

	return items;
}

/**
 * Find [DONE:id] tags in text and return the IDs.
 */
function findDoneTags(text: string): string[] {
	const pattern = /\[DONE:([a-z0-9]+)\]/gi;
	const ids: string[] = [];
	for (const match of text.matchAll(pattern)) {
		ids.push(match[1].toLowerCase());
	}
	return ids;
}

export default function planModeHook(pi: HookAPI) {
	let planModeEnabled = false;
	let executionMode = false;
	let todoItems: TodoItem[] = [];

	// Register --plan CLI flag
	pi.registerFlag("plan", {
		description: "Start in plan mode (read-only exploration)",
		type: "boolean",
		default: false,
	});

	// Helper to update status displays
	function updateStatus(ctx: HookContext) {
		if (executionMode && todoItems.length > 0) {
			const completed = todoItems.filter((t) => t.completed).length;
			ctx.ui.setStatus("plan-mode", ctx.ui.theme.fg("accent", `📋 ${completed}/${todoItems.length}`));
		} else if (planModeEnabled) {
			ctx.ui.setStatus("plan-mode", ctx.ui.theme.fg("warning", "⏸ plan"));
		} else {
			ctx.ui.setStatus("plan-mode", undefined);
		}

		// Show widget during execution
		if (executionMode && todoItems.length > 0) {
			const lines: string[] = [];
			for (const item of todoItems) {
				if (item.completed) {
					lines.push(
						ctx.ui.theme.fg("success", "☑ ") + ctx.ui.theme.fg("muted", ctx.ui.theme.strikethrough(item.text)),
					);
				} else {
					lines.push(ctx.ui.theme.fg("muted", "☐ ") + item.text);
				}
			}
			ctx.ui.setWidget("plan-todos", lines);
		} else {
			ctx.ui.setWidget("plan-todos", undefined);
		}
	}

	function togglePlanMode(ctx: HookContext) {
		planModeEnabled = !planModeEnabled;
		executionMode = false;
		todoItems = [];

		if (planModeEnabled) {
			pi.setTools(PLAN_MODE_TOOLS);
			ctx.ui.notify(`Plan mode enabled. Tools: ${PLAN_MODE_TOOLS.join(", ")}`);
		} else {
			pi.setTools(NORMAL_MODE_TOOLS);
			ctx.ui.notify("Plan mode disabled. Full access restored.");
		}
		updateStatus(ctx);
	}

	// Register /plan command
	pi.registerCommand("plan", {
		description: "Toggle plan mode (read-only exploration)",
		handler: async (_args, ctx) => {
			togglePlanMode(ctx);
		},
	});

	// Register /todos command
	pi.registerCommand("todos", {
		description: "Show current plan todo list",
		handler: async (_args, ctx) => {
			if (todoItems.length === 0) {
				ctx.ui.notify("No todos. Create a plan first with /plan", "info");
				return;
			}

			const todoList = todoItems
				.map((item) => {
					const checkbox = item.completed ? "✓" : "○";
					return `[${item.id}] ${checkbox} ${item.text}`;
				})
				.join("\n");

			ctx.ui.notify(`Plan Progress:\n${todoList}`, "info");
		},
	});

	// Register Shift+P shortcut
	pi.registerShortcut("shift+p", {
		description: "Toggle plan mode",
		handler: async (ctx) => {
			togglePlanMode(ctx);
		},
	});

	// Block destructive bash in plan mode
	pi.on("tool_call", async (event) => {
		if (!planModeEnabled) return;
		if (event.toolName !== "bash") return;

		const command = event.input.command as string;
		if (!isSafeCommand(command)) {
			return {
				block: true,
				reason: `Plan mode: destructive command blocked. Use /plan to disable plan mode first.\nCommand: ${command}`,
			};
		}
	});

	// Buffer for accumulating text to handle [DONE:id] split across chunks
	let textBuffer = "";

	// Watch for [DONE:id] tags in streaming text
	pi.on("text_delta", async (event, ctx) => {
		if (!executionMode || todoItems.length === 0) return;

		// Accumulate text in buffer
		textBuffer += event.text;

		// Look for complete [DONE:id] patterns
		const doneIds = findDoneTags(textBuffer);
		if (doneIds.length === 0) return;

		let changed = false;
		for (const id of doneIds) {
			const item = todoItems.find((t) => t.id === id);
			if (item && !item.completed) {
				item.completed = true;
				changed = true;
			}
		}

		// Clear processed patterns from buffer (keep last 20 chars for partial matches)
		if (textBuffer.length > 50) {
			textBuffer = textBuffer.slice(-20);
		}

		if (changed) {
			updateStatus(ctx);
		}
	});

	// Inject plan mode context
	pi.on("before_agent_start", async () => {
		if (!planModeEnabled && !executionMode) return;

		if (planModeEnabled) {
			return {
				message: {
					customType: "plan-mode-context",
					content: `[PLAN MODE ACTIVE]
You are in plan mode - a read-only exploration mode for safe code analysis.

Restrictions:
- You can only use: read, bash, grep, find, ls
- You CANNOT use: edit, write (file modifications are disabled)
- Bash is restricted to READ-ONLY commands
- Focus on analysis, planning, and understanding the codebase

Create a detailed numbered plan:
1. First step description
2. Second step description
...

Do NOT attempt to make changes - just describe what you would do.`,
					display: false,
				},
			};
		}

		if (executionMode && todoItems.length > 0) {
			const todoList = todoItems.map((t) => `- [${t.id}] ${t.completed ? "☑" : "☐"} ${t.text}`).join("\n");
			return {
				message: {
					customType: "plan-execution-context",
					content: `[EXECUTING PLAN]
You have a plan with ${todoItems.length} steps. After completing each step, output [DONE:id] to mark it complete.

Current plan status:
${todoList}

IMPORTANT: After completing each step, output [DONE:id] where id is the step's ID (e.g., [DONE:${todoItems.find((t) => !t.completed)?.id || todoItems[0].id}]).`,
					display: false,
				},
			};
		}
	});

	// After agent finishes in plan mode
	pi.on("agent_end", async (event, ctx) => {
		// Clear text buffer
		textBuffer = "";

		// Check for done tags in the final message too
		if (executionMode && todoItems.length > 0) {
			const messages = event.messages;
			const lastAssistant = [...messages].reverse().find((m) => m.role === "assistant");
			if (lastAssistant && Array.isArray(lastAssistant.content)) {
				const textContent = lastAssistant.content
					.filter((block): block is { type: "text"; text: string } => block.type === "text")
					.map((block) => block.text)
					.join("\n");

				const doneIds = findDoneTags(textContent);
				for (const id of doneIds) {
					const item = todoItems.find((t) => t.id === id);
					if (item && !item.completed) {
						item.completed = true;
					}
				}
				updateStatus(ctx);
			}

			// Check if all complete
			const allComplete = todoItems.every((t) => t.completed);
			if (allComplete) {
				// Show final completed list in chat
				const completedList = todoItems
					.map((t) => `~~${t.text}~~`)
					.join("\n");
				pi.sendMessage(
					{
						customType: "plan-complete",
						content: `**Plan Complete!** ✓\n\n${completedList}`,
						display: true,
					},
					{ triggerTurn: false },
				);

				executionMode = false;
				const completedItems = [...todoItems]; // Keep for reference
				todoItems = [];
				pi.setTools(NORMAL_MODE_TOOLS);
				updateStatus(ctx);
			}
			return;
		}

		if (!planModeEnabled) return;
		if (!ctx.hasUI) return;

		// Extract todos from last message
		const messages = event.messages;
		const lastAssistant = [...messages].reverse().find((m) => m.role === "assistant");
		if (lastAssistant && Array.isArray(lastAssistant.content)) {
			const textContent = lastAssistant.content
				.filter((block): block is { type: "text"; text: string } => block.type === "text")
				.map((block) => block.text)
				.join("\n");

			if (textContent) {
				const extracted = extractTodoItems(textContent);
				if (extracted.length > 0) {
					todoItems = extracted;
				}
			}
		}

		const hasTodos = todoItems.length > 0;

		// Show todo list in chat with IDs
		if (hasTodos) {
			const todoListText = todoItems.map((t) => `☐ [${t.id}] ${t.text}`).join("\n");
			pi.sendMessage(
				{
					customType: "plan-todo-list",
					content: `**Plan Steps (${todoItems.length}):**\n\n${todoListText}`,
					display: true,
				},
				{ triggerTurn: false },
			);
		}

		const choice = await ctx.ui.select("Plan mode - what next?", [
			hasTodos ? "Execute the plan (track progress)" : "Execute the plan",
			"Stay in plan mode",
			"Refine the plan",
		]);

		if (choice?.startsWith("Execute")) {
			planModeEnabled = false;
			executionMode = hasTodos;
			pi.setTools(NORMAL_MODE_TOOLS);
			updateStatus(ctx);

			const execMessage = hasTodos
				? `Execute the plan. After completing each step, output [DONE:id] where id is the step's ID. Start with step [${todoItems[0].id}]: ${todoItems[0].text}`
				: "Execute the plan you just created. Proceed step by step.";

			pi.sendMessage(
				{
					customType: "plan-mode-execute",
					content: execMessage,
					display: true,
				},
				{ triggerTurn: true },
			);
		} else if (choice === "Refine the plan") {
			const refinement = await ctx.ui.input("What should be refined?");
			if (refinement) {
				ctx.ui.setEditorText(refinement);
			}
		}
	});

	// Initialize state on session start
	pi.on("session_start", async (_event, ctx) => {
		if (pi.getFlag("plan") === true) {
			planModeEnabled = true;
		}

		const entries = ctx.sessionManager.getEntries();
		const planModeEntry = entries
			.filter((e: { type: string; customType?: string }) => e.type === "custom" && e.customType === "plan-mode")
			.pop() as { data?: { enabled: boolean; todos?: TodoItem[]; executing?: boolean } } | undefined;

		if (planModeEntry?.data) {
			if (planModeEntry.data.enabled !== undefined) {
				planModeEnabled = planModeEntry.data.enabled;
			}
			if (planModeEntry.data.todos) {
				todoItems = planModeEntry.data.todos;
			}
			if (planModeEntry.data.executing) {
				executionMode = planModeEntry.data.executing;
			}
		}

		if (planModeEnabled) {
			pi.setTools(PLAN_MODE_TOOLS);
		}
		updateStatus(ctx);
	});

	// Persist state
	pi.on("turn_start", async () => {
		pi.appendEntry("plan-mode", {
			enabled: planModeEnabled,
			todos: todoItems,
			executing: executionMode,
		});
	});
}