/**
 * pi-worktree Extension
 *
 * Manages git worktrees through tool commands and an interactive `/worktree` command.
 *
 * Tools:
 * - git_worktree_create — Create a linked worktree for a branch
 * - git_worktree_list — List all linked worktrees
 * - git_worktree_switch — Switch working directory to a worktree
 * - git_worktree_remove — Remove a linked worktree
 *
 * Command:
 * - /worktree — Interactive picker to switch between worktrees
 */

import type { ExtensionAPI, ExtensionContext } from "@earendil-works/pi-coding-agent";
import { defineTool } from "@earendil-works/pi-coding-agent";
import { Type } from "@earendil-works/pi-ai";
import { parseWorktreeList, type WorktreeEntry } from "./pi-worktree-parser";

// ─── Type Definitions ──────────────────────────────────────────────

/** Result of listing all worktrees. */
interface WorktreeListResult {
	/** All worktrees in the repository. */
	worktrees: WorktreeEntry[];
	/** Number of worktrees found. */
	count: number;
	/** Current working directory used for comparison. */
	currentPath: string;
}

/** Error returned when a worktree operation fails. */
interface WorktreeError {
	/** Human-readable error message from git or validation. */
	message: string;
	/** Suggested fix for the user. */
	suggestion?: string;
}

// ─── Tool Parameter Schemas ────────────────────────────────────────

const createWorktreeParams = Type.Object({
	path: Type.String({ description: "Path for the new worktree (relative or absolute)" }),
	branch: Type.Optional(Type.String({ description: "Branch name to check out. Defaults to 'main'." })),
	create_branch: Type.Optional(
		Type.Boolean({
			description: "If true and branch doesn't exist, create it. Defaults to false.",
		}),
	),
});

const listWorktreeParams = Type.Object({});

const switchWorktreeParams = Type.Object({
	target: Type.String({ description: "Path or branch name of the target worktree to switch to." }),
});

const removeWorktreeParams = Type.Object({
	path: Type.String({ description: "Path of the worktree to remove." }),
});

// ─── Helper Functions (stubs) ──────────────────────────────────────

/**
 * Check if the target path exists.
 * @param checkPath - Path to check
 * @param ctx - Extension context for file system access
 * @returns True if the path exists
 */
async function pathExists(checkPath: string, ctx: ExtensionContext): Promise<boolean> {
	throw new Error("not implemented");
}

/**
 * Resolve a worktree target (path or branch name) to its full path.
 * @param target - Path or branch name to resolve
 * @param worktrees - List of all worktrees
 * @returns The resolved path, or undefined if not found
 */
function resolveWorktreeTarget(target: string, worktrees: WorktreeEntry[]): string | undefined {
	throw new Error("not implemented");
}

// ─── Tool Factories ────────────────────────────────────────────────

/**
 * Create the git_worktree_create tool definition.
 * @param pi - Extension API for registering and executing tools
 * @returns The configured tool definition
 */
function createListWorktreeTool(pi: ExtensionAPI) {
	return defineTool({
		name: "git_worktree_list",
		label: "Git Worktree List",
		description: "List all linked worktrees in the current repo.",
		parameters: listWorktreeParams,
		async execute(_toolCallId, _params, _signal, _onUpdate, ctx) {
			const result = await pi.exec("git", ["worktree", "list"], { cwd: ctx.cwd });

			if (result.exitCode !== 0) {
				return {
					content: [{ type: "text", text: `Error listing worktrees: ${result.stderr}. Suggestion: Ensure you are inside a git repository.` }],
					isError: true,
				};
			}

			const worktreeEntries = parseWorktreeList(result.stdout, ctx.cwd);

			if (worktreeEntries.length === 0) {
				return {
					content: [{ type: "text", text: "No worktrees found." }],
					details: <WorktreeListResult>{
						worktrees: [],
						count: 0,
						currentPath: ctx.cwd,
						warning: "No worktrees exist. Use git_worktree_create to add one.",
					},
				};
			}

			const displayLines = worktreeEntries.map(
				(entry) => `${entry.branch} - ${entry.path}${entry.isCurrent ? " (current)" : ""}`,
			);

			return {
				content: [{ type: "text", text: displayLines.join("\n") }],
				details: <WorktreeListResult>{
					worktrees: worktreeEntries,
					count: worktreeEntries.length,
					currentPath: ctx.cwd,
				},
			};
		},
	});
}

/**
 * Create the git_worktree_create tool definition.
 * @param _pi - Extension API (unused in stub)
 * @returns The configured tool definition
 */
function createCreateWorktreeTool(_pi: ExtensionAPI) {
	return defineTool({
		name: "git_worktree_create",
		label: "Git Worktree Create",
		description: "Create a linked worktree for a branch in the current repo.",
		parameters: createWorktreeParams,
		async execute(_toolCallId, _params, _signal, _onUpdate, _ctx) {
			return {
				content: [{ type: "text", text: "Error: git_worktree_create is not yet implemented. Suggestion: Use `git worktree add` manually until this tool is complete." }],
				isError: true,
			};
		},
	});
}

/**
 * Create the git_worktree_switch tool definition.
 * @param _pi - Extension API (unused in stub)
 * @returns The configured tool definition
 */
function createSwitchWorktreeTool(_pi: ExtensionAPI) {
	return defineTool({
		name: "git_worktree_switch",
		label: "Git Worktree Switch",
		description: "Switch pi's working directory to a linked worktree.",
		parameters: switchWorktreeParams,
		async execute(_toolCallId, _params, _signal, _onUpdate, _ctx) {
			return {
				content: [{ type: "text", text: "Error: git_worktree_switch is not yet implemented. Suggestion: Use the `/worktree` command or `git worktree` manually until this tool is complete." }],
				isError: true,
			};
		},
	});
}

/**
 * Create the git_worktree_remove tool definition.
 * @param _pi - Extension API (unused in stub)
 * @returns The configured tool definition
 */
function createRemoveWorktreeTool(_pi: ExtensionAPI) {
	return defineTool({
		name: "git_worktree_remove",
		label: "Git Worktree Remove",
		description: "Remove a linked worktree.",
		parameters: removeWorktreeParams,
		async execute(_toolCallId, _params, _signal, _onUpdate, _ctx) {
			return {
				content: [{ type: "text", text: "Error: git_worktree_remove is not yet implemented. Suggestion: Use `git worktree remove` manually until this tool is complete." }],
				isError: true,
			};
		},
	});
}

// ─── Extension Entry Point ────────────────────────────────────────

export default function (pi: ExtensionAPI) {
	// Register tools via factory functions
	pi.registerTool(createCreateWorktreeTool(pi));
	pi.registerTool(createListWorktreeTool(pi));
	pi.registerTool(createSwitchWorktreeTool(pi));
	pi.registerTool(createRemoveWorktreeTool(pi));

	// ─── Command Registration ──────────────────────────────────────
	pi.registerCommand("worktree", {
		description: "Interactive picker to switch between linked worktrees.",
		handler: async (_args, _ctx) => {
			return {
				content: [{ type: "text", text: "Error: /worktree command is not yet implemented. Suggestion: Use `git worktree list` and navigate manually until this command is complete." }],
				isError: true,
			};
		},
	});
}