using System;
using UnityEngine;

namespace LLM.Commands
{
    public static class LLMCommandParser
    {
        public static bool TryExtract(string rawReply, out string visibleText, out LLMCommandEnvelope envelope)
        {
            visibleText = rawReply ?? "";
            envelope = null;

            if (string.IsNullOrWhiteSpace(rawReply)) return false;

            string cleaned = rawReply.Replace("```json", "").Replace("```", "").Trim();

            if (TryParseEnvelope(cleaned, out envelope))
            {
                visibleText = string.IsNullOrWhiteSpace(envelope.text) ? "" : envelope.text.Trim();
                return true;
            }

            if (!TryExtractLastJsonObject(cleaned, out string json, out int startIndex)) return false;

            if (!TryParseEnvelope(json, out envelope)) return false;

            visibleText = string.IsNullOrWhiteSpace(envelope.text)
                ? cleaned.Substring(0, startIndex).Trim()
                : envelope.text.Trim();

            return true;
        }

        private static bool TryParseEnvelope(string json, out LLMCommandEnvelope envelope)
        {
            envelope = null;
            try
            {
                envelope = JsonUtility.FromJson<LLMCommandEnvelope>(json);
            }
            catch (Exception)
            {
                envelope = null;
            }

            if (envelope == null) return false;
            if (envelope.commands == null && string.IsNullOrWhiteSpace(envelope.text)) return false;
            return true;
        }

        private static bool TryExtractLastJsonObject(string input, out string json, out int startIndex)
        {
            json = null;
            startIndex = -1;

            if (string.IsNullOrEmpty(input)) return false;

            int end = input.LastIndexOf('}');
            if (end < 0) return false;

            int depth = 0;
            for (int i = end; i >= 0; i--)
            {
                char c = input[i];
                if (c == '}') depth++;
                else if (c == '{')
                {
                    depth--;
                    if (depth == 0)
                    {
                        startIndex = i;
                        json = input.Substring(i, end - i + 1);
                        return true;
                    }
                }
            }

            return false;
        }
    }
}