/**
 * 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";

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

/** A single worktree entry parsed from `git worktree list`. */
interface WorktreeEntry {
	/** Full path to the worktree directory. */
	path: string;
	/** Short commit hash checked out in this worktree. */
	commit: string;
	/** Branch name, or "(detached)" for detached HEAD. */
	branch: string;
	/** Whether this worktree is the current working directory. */
	isCurrent: boolean;
}

/** Result of listing all worktrees. */
interface WorktreeListResult {
	/** All worktrees in the repository. */
	worktrees: WorktreeEntry[];
	/** Total number of worktrees. */
	count: number;
}

/** 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) ──────────────────────────────────────

/**
 * Parse raw `git worktree list` output into structured entries.
 * @param rawOutput - Raw stdout from `git worktree list`
 * @param currentDir - Current working directory for comparison
 * @returns Array of parsed worktree entries
 */
function parseWorktreeList(rawOutput: string, currentDir: string): WorktreeEntry[] {
	throw new Error("not implemented");
}

/**
 * Check if the target path exists.
 * @param path - Path to check
 * @param ctx - Extension context for file system access
 * @returns True if the path exists
 */
async function pathExists(path: 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 Definitions ──────────────────────────────────────────────

const gitWorktreeCreateTool = 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) {
		throw new Error("not implemented");
	},
});

const gitWorktreeListTool = 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) {
		throw new Error("not implemented");
	},
});

const gitWorktreeSwitchTool = 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) {
		throw new Error("not implemented");
	},
});

const gitWorktreeRemoveTool = defineTool({
	name: "git_worktree_remove",
	label: "Git Worktree Remove",
	description: "Remove a linked worktree.",
	parameters: removeWorktreeParams,
	async execute(_toolCallId, _params, _signal, _onUpdate, _ctx) {
		throw new Error("not implemented");
	},
});

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

export default function (pi: ExtensionAPI) {
	// Register tools
	pi.registerTool(gitWorktreeCreateTool);
	pi.registerTool(gitWorktreeListTool);
	pi.registerTool(gitWorktreeSwitchTool);
	pi.registerTool(gitWorktreeRemoveTool);

	// Register /worktree command
	pi.registerCommand("worktree", {
		description: "Interactive picker to switch between linked worktrees.",
		handler: async (_args, _ctx) => {
			throw new Error("not implemented");
		},
	});
}