using Newtonsoft.Json.Linq;
using System.Collections.Generic;

public static class GoogleSheetDiffHelper
{
    public static List<(string Sheet, string Field, int RowIndex, string OldValue, string NewValue)> CompareJsonDiff(string oldJson, string newJson)
    {
        var diffs = new List<(string, string, int, string, string)>();

        if (string.IsNullOrEmpty(oldJson) || string.IsNullOrEmpty(newJson))
            return diffs;

        var oldObj = JObject.Parse(oldJson);
        var newObj = JObject.Parse(newJson);

        foreach (var sheet in newObj)
        {
            var sheetName = sheet.Key;
            if (!oldObj.TryGetValue(sheetName, out var oldSheetToken))
                continue;

            var oldArray = oldSheetToken as JArray;
            var newArray = sheet.Value as JArray;

            // Row-by-row 비교 (1번 줄부터 데이터 시작)
            for (int i = 1; i < newArray.Count; i++)
            {
                if (i >= oldArray.Count)
                    break;

                var newRow = (JObject)newArray[i];
                var oldRow = (JObject)oldArray[i];

                foreach (var prop in newRow.Properties())
                {
                    var field = prop.Name;
                    string newValue = prop.Value.ToString();
                    string oldValue = oldRow.TryGetValue(field, out var oldVal) ? oldVal.ToString() : "";

                    if (oldValue != newValue)
                    {
                        diffs.Add((sheetName, field, i, oldValue, newValue));
                    }
                }
            }
        }

        return diffs;
    }

    public static string GenerateDiff(string oldJson, string newJson)
    {
        var diffs = CompareJsonDiff(oldJson, newJson);
        if (diffs.Count == 0)
            return "No differences found.";

        var sb = new System.Text.StringBuilder();
        sb.AppendLine("[GoogleSheetManager] 변경된 필드들:");

        foreach (var (sheet, field, rowIndex, oldVal, newVal) in diffs)
        {
            sb.AppendLine($"{sheet} / Row {rowIndex} / {field} : '{oldVal}' → '{newVal}'");
        }

        return sb.ToString();
    }
}