/**
 * Models.json resolution with fallback to ~/.pi/agent/models.json
 *
 * SF uses ~/.sf/agent/models.json, but for a smooth migration/development
 * experience, this module provides resolution logic that:
 *
 * 1. Reads ~/.sf/agent/models.json if it exists
 * 2. Falls back to ~/.pi/agent/models.json if SF file doesn't exist
 * 3. Merges both files if both exist (SF takes precedence)
 */

import { existsSync } from "node:fs";
import { homedir } from "node:os";
import { join } from "node:path";
import { agentDir } from "./app-paths.js";

const SF_MODELS_PATH = join(agentDir, "models.json");
const PI_MODELS_PATH = join(homedir(), ".pi", "agent", "models.json");

/**
 * Resolve the path to models.json with fallback logic.
 *
 * Priority:
 * 1. ~/.sf/agent/models.json (exists) → return this path
 * 2. ~/.pi/agent/models.json (exists) → return this path (fallback)
 * 3. Neither exists → return SF path (will be created)
 *
 * @returns The path to use for models.json
 */
export function resolveModelsJsonPath(): string {
	if (existsSync(SF_MODELS_PATH)) {
		return SF_MODELS_PATH;
	}
	if (existsSync(PI_MODELS_PATH)) {
		return PI_MODELS_PATH;
	}
	return SF_MODELS_PATH;
}