using System.Reflection.PortableExecutable;
using System.Text;
using System.Text.RegularExpressions;
using ConsoleApp2.Helpers;
using ConsoleApp2.HostedServices.Abstractions;
using Microsoft.Extensions.Logging;

namespace ConsoleApp2.Services;

/// <summary>
/// CSV文件读取
/// </summary>
public class CsvSource:IDataSource
{
    protected readonly string _inputDir;
    //protected readonly StreamReader _reader;
    private readonly ILogger? _logger;
    protected readonly string _tableName;
    protected  string _sqlFilePath=string.Empty;
    protected readonly string? _sqlFileText;
    protected string[] headers=Array.Empty<string>();
    protected string[] csvFiles = Array.Empty<string>();
    public string? CurrentRaw { get; protected set; }
    public string Delimiter { get; private set; }
    public char QuoteChar { get; private set; }
    public CsvSource(string inputDir,string tableName,string delimiter = ",", char quoteChar = '"',
        ILogger? logger = null)
    {
        _inputDir = inputDir;
        _tableName = tableName;
        _logger = logger;
        Delimiter = delimiter;
        QuoteChar = quoteChar;

    }


    public string[] ParseRow(string row, char quoteChar, string delimiter)
    {
        var span = row.AsSpan();
        var result = new List<string>();

        if (span.Length == 0)
            throw new ArgumentException("The row is empty", nameof(row));

        var isInQuote = span[0] == quoteChar;
        var start = 0;
        for (var i = 1; i < span.Length; i++)
        {
            if (span[i] == quoteChar)
            {
                isInQuote = !isInQuote;
            }
            // delimiter需要足够复杂
            else if (/*!isInQuote && */span.Length > i + delimiter.Length && span[i..(i + delimiter.Length)].Equals(delimiter, StringComparison.CurrentCulture)) // field matched
            {
                string field;
                if (span[start] == quoteChar && span[i - 1] == quoteChar) // enclosed by quoteChar
                    field = span[(start + 1)..(i - 1)].ToString(); // escape quoteChar
                else
                    field = span[start..i].ToString();

                start = i + delimiter.Length;

                if (field == "\\N")
                    field = "NULL";

                result.Add(field);
                
                continue;
            }
        }

        result.Add(span[start..].ToString());


        for (var i = 0; i < result.Count; i++)
        {
            var field = result[i];
            if (DumpDataHelper.CheckHexField(field) && StringExtensions.CheckJsonHex(field))
            {
                result[i] = StringExtensions.FromHex(field);
            }
        }

        return result.ToArray();
    }
    
    public string[] ParseRow2(ReadOnlySpan<char> source, char quoteChar, string delimiter)
    {
        var result = new List<string>();
        var index = -1;
        StringBuilder current = new StringBuilder();
        bool hasQuote = false;
        bool hasSlash = false;
        while (index < source.Length-1)
        {
            index++;
            if (hasSlash == false && source[index] == '\\')
            {
                hasSlash = true;
                current.Append('\\');
                continue;
            }
            if (hasSlash ==false && source[index] == quoteChar)
            {
                hasQuote = !hasQuote;
                current.Append(source[index]);
                continue;
            }
            if (hasQuote==false && source[index] == delimiter[0])
            {
                result.Add(current.ToString());
                current.Clear();
            }
            else
            {
                current.Append(source[index]);
            }

            hasSlash = false;
        }

        result.Add(current.ToString());
        return result.ToArray();
    }
    public virtual async Task GetHeaderAndCsvFiles()
    {
        string pattern = $"^.*\\.{_tableName}\\..*\\.sql$";
        _sqlFilePath = Directory.GetFiles(_inputDir).FirstOrDefault(s => Regex.Match(s, pattern).Success) ?? "";
        var text = await File.ReadAllTextAsync(_sqlFilePath);
        headers =  DumpDataHelper.GetCsvHeadersFromSqlFileAsync(text);
        csvFiles =  DumpDataHelper.GetCsvFileNamesFromSqlFileAsync(text, new Regex(@"'.+\.dat.zst'"));

    }
    public virtual async Task DoEnqueue(Action<DataRecord> action)
    {
        await GetHeaderAndCsvFiles();
        foreach (var file in csvFiles)
        {
            var filePath= Path.Combine(_inputDir, file);
            using var fs = File.OpenRead(filePath);
            {
                using StreamReader sr = new (fs);
                {
                    while (!sr.EndOfStream)
                    {
                        var line = await sr.ReadLineAsync();
                        var fields = ParseRow2(line, QuoteChar, Delimiter);
                        var record = new DataRecord(fields, _tableName, headers);
                        action?.Invoke(record);
                    }
                }
            }

          
        }
    }
    public virtual async Task<DataRecord?> GetTestRecord()
    {
        await GetHeaderAndCsvFiles();
        var file = csvFiles.FirstOrDefault();
        if (file != null)
        {
            var filePath = Path.Combine(_inputDir, file);
            using var fs = File.OpenRead(filePath);
            {
                using StreamReader sr = new(fs);
                {
                    var line = await sr.ReadLineAsync();
                    var fields = ParseRow2(line, QuoteChar, Delimiter);
                    var record = new DataRecord(fields, _tableName, headers);
                    return record;
                }
            } 
        }
        return null;
    }
    public void Dispose()
    {
       // _reader.Dispose();
    }
}