using System;
using System.Collections.Generic;
using System.IO;
using System.Text.Json;
using System.Threading.Tasks;
using Toak.Serialization;
using Toak.Core.Interfaces;

namespace Toak.Core;

public class HistoryManager : IHistoryManager
{
    private readonly string HistoryDir = Constants.Paths.AppDataDir;
    private readonly string HistoryFile = Constants.Paths.HistoryFile;

    public HistoryManager()
    {
    }

    public void SaveEntry(string rawTranscript, string refinedText, string? skillName, long durationMs)
    {
        try
        {
            if (!Directory.Exists(HistoryDir))
            {
                Directory.CreateDirectory(HistoryDir);
            }

            var entry = new HistoryEntry
            {
                Timestamp = DateTime.UtcNow,
                RawTranscript = rawTranscript,
                RefinedText = refinedText,
                SkillName = skillName,
                DurationMs = durationMs
            };

            var json = JsonSerializer.Serialize(entry, CompactJsonSerializerContext.Default.HistoryEntry);
            
            // Thread-safe append
            lock (HistoryFile)
            {
                File.AppendAllLines(HistoryFile, new[] { json });
            }
        }
        catch (Exception ex)
        {
            Logger.LogDebug($"Failed to save history: {ex.Message}");
        }
    }

    public List<HistoryEntry> LoadHistory()
    {
        var entries = new List<HistoryEntry>();
        if (!File.Exists(HistoryFile)) return entries;

        try
        {
            string[] lines;
            lock (HistoryFile)
            {
                lines = File.ReadAllLines(HistoryFile);
            }

            foreach (var line in lines)
            {
                if (string.IsNullOrWhiteSpace(line)) continue;
                if (!line.Trim().StartsWith("{") || !line.Trim().EndsWith("}")) continue; // Skip malformed old multiline json entries

                try 
                {
                    var entry = JsonSerializer.Deserialize(line, CompactJsonSerializerContext.Default.HistoryEntry);
                    if (entry != null)
                    {
                        entries.Add(entry);
                    }
                }
                catch 
                {
                    // Skip entry if deserialization fails
                }
            }
        }
        catch (Exception ex)
        {
            Console.WriteLine($"CRASH IN LOAD ENTRIES: {ex}");
            Logger.LogDebug($"Failed to load history: {ex.Message}");
        }

        return entries;
    }

    public void ClearHistory()
    {
        if (File.Exists(HistoryFile))
        {
            try
            {
                lock (HistoryFile)
                {
                    // Securely delete
                    var len = new FileInfo(HistoryFile).Length;
                    using (var fs = new FileStream(HistoryFile, FileMode.Open, FileAccess.Write))
                    {
                        var blank = new byte[len];
                        fs.Write(blank, 0, blank.Length);
                    }
                    File.Delete(HistoryFile);
                }
            }
            catch (Exception ex)
            {
                Logger.LogDebug($"Failed to shred history: {ex.Message}");
            }
        }
    }
}