/**
 * Git worktree switch — pure validation and resolution functions.
 * No pi SDK dependencies for testability.
 */

import path from "path";
import type { WorktreeError } from "./pi-worktree-create";
import type { WorktreeEntry } from "./pi-worktree-parser";

// ─── Input Validation ──────────────────────────────────────────────

/**
 * Validate input parameters for switching worktrees.
 *
 * Checks that target is non-empty and well-formed.
 *
 * @param target - Path or branch name of the target worktree
 * @returns null if valid, or a WorktreeError describing the problem
 */
export function validateSwitchInput(target: string): WorktreeError | null {
	if (!target || !target.trim()) {
		return {
			message: "Target cannot be empty.",
			suggestion: "Provide a valid worktree path or branch name. Use git_worktree_list to see available worktrees.",
		};
	}

	return null;
}

// ─── Target Resolution ──────────────────────────────────────────────

/**
 * Resolve a worktree target (path or branch name) to its full path.
 *
 * First tries an exact path match, then falls back to branch name lookup.
 *
 * @param target - Path or branch name to resolve
 * @param worktrees - List of all worktrees
 * @returns The resolved path, or undefined if not found
 */
export function resolveWorktreeTarget(
	target: string,
	worktrees: WorktreeEntry[],
): string | undefined {
	// Try exact path match first
	const exactMatch = worktrees.find((w) => w.path === target);
	if (exactMatch) return exactMatch.path;

	// Fall back to branch name match
	const branchMatch = worktrees.find((w) => w.branch === target);
	return branchMatch?.path;
}

// ─── Already-There Check ───────────────────────────────────────────

/**
 * Check if the current working directory is already the target worktree.
 *
 * Compares resolved paths to handle trailing slashes and relative paths.
 *
 * @param targetPath - The target worktree path
 * @param currentCwd - Current working directory
 * @returns true if already in the target worktree
 */
export function isAlreadyInWorktree(targetPath: string, currentCwd: string): boolean {
	return path.resolve(currentCwd, targetPath) === path.resolve(currentCwd);
}