using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using MiniExcelLibs;
using StackExchange.Redis; // We'll just use IDatabase interface if possible, or dependency injection.
                           // For now, let's keep it simple and pass the db/batch or connection string.
                           // Better yet, pass an interface IStorageWrapper.

namespace ExcelKv.Core;

// Simple Config DTO for user-defined areas
public class RegionConfig
{
    public int TopHeaderStartRow { get; set; } = 0;
    public int TopHeaderDepth { get; set; } = 3;
    public int LeftHeaderStartCol { get; set; } = 0;
    public int LeftHeaderWidth { get; set; } = 4;
}

public interface IStorageWrapper
{
    Task SetAsync(string key, string value);
    Task IncrementAsync(string key, double value);
}

// Live Aggregator Helper (Moved here for shared access)
public class LiveAggregator
{
    // Simple basic check for now. Can be expanded.
    private static readonly System.Text.RegularExpressions.Regex MetricPattern = 
        new System.Text.RegularExpressions.Regex(@"(수량|합계|Volume|Weight|Total|Usage)", System.Text.RegularExpressions.RegexOptions.IgnoreCase | System.Text.RegularExpressions.RegexOptions.Compiled);

    public static bool IsMetric(string colName) => MetricPattern.IsMatch(colName);
    
    public static string GenerateGroupKey(string sheetName, string category, string spec, string metricName)
        => $"Stats:{Use_(category)}:{Use_(spec)}:{Use_(metricName)}";
        
    private static string Use_(string s) => string.IsNullOrWhiteSpace(s) ? "Unknown" : s.Replace(" ", "_");
}


public class ExcelLoader
{
    public static async Task<int> ProcessFileAsync(
        string filePath, 
        string sheetName, 
        RegionConfig config, 
        IStorageWrapper storage, 
        SchemaRegistry registry)
    {
        Console.WriteLine($"[Core.Loader] Processing {filePath} Sheet: {sheetName}...");
        Console.WriteLine($"[Config] Top: Row{config.TopHeaderStartRow} (+{config.TopHeaderDepth}), Left: Col{config.LeftHeaderStartCol} (+{config.LeftHeaderWidth})");
        
        var rows = MiniExcel.Query(filePath, sheetName: sheetName, useHeaderRow: false).ToList();
        
        // Validation
        int dataStartRow = config.TopHeaderStartRow + config.TopHeaderDepth;
        if (rows.Count <= dataStartRow) return 0;

        // 1. Analyze Top Headers
        // Extract the rows that form the Top Header
        List<string[]> topHeaderRows = new();
        for (int i = config.TopHeaderStartRow; i < dataStartRow; i++)
        {
             var rowDict = (IDictionary<string, object>)rows[i];
             topHeaderRows.Add(FlattenDictionaryRow(rowDict));
        }
        
        // Flatten Top Headers (Horizontal Forward Fill)
        // Offset: We effectively care about columns starting from LeftHeaderWidth to End
        // but we pass the absolute index.
        var topAxisKeys = FlattenTopHeaders(topHeaderRows, config.LeftHeaderStartCol + config.LeftHeaderWidth);
        
        // Register Schema
        string ns = System.IO.Path.GetFileName(filePath) + "_" + sheetName;
        registry.RegisterSchema(ns, topAxisKeys);

        // 2. Process Data Rows
        // State for Vertical Forward Fill (Left Headers)
        string[] lastLeftValues = new string[config.LeftHeaderWidth];

        int processedCount = 0;

        for (int i = dataStartRow; i < rows.Count; i++)
        {
            var rowDict = (IDictionary<string, object>)rows[i];
            var rowVals = FlattenDictionaryRow(rowDict);
            
            // A. Build Left Axis Key (Vertical Forward Fill)
            var currentLeftParts = new List<string>();
            bool rowHasContent = false;
            
            for (int c = 0; c < config.LeftHeaderWidth; c++)
            {
                int absCol = config.LeftHeaderStartCol + c;
                string val = (absCol < rowVals.Length) ? rowVals[absCol] : "";
                
                // Logic: Unmerge & Fill (Same as Vertical Forward Fill)
                if (string.IsNullOrWhiteSpace(val))
                {
                     val = lastLeftValues[c];
                }
                else
                {
                     lastLeftValues[c] = val; // New merge block starts
                }
                
                if(!string.IsNullOrWhiteSpace(val)) 
                {
                    currentLeftParts.Add(val);
                    rowHasContent = true;
                }
            }
            
            // Skip rows with no left context (e.g. empty separator lines)
            if (!rowHasContent) continue; 

            string leftKey = string.Join(".", currentLeftParts);

            // B. Map Values to Top Axis Keys
            for (int c = config.LeftHeaderStartCol + config.LeftHeaderWidth; c < rowVals.Length; c++)
            {
                // Align physical column to Top Axis Index
                // Top Axis Keys[0] corresponds to column (LeftStart + LeftWidth)
                int topIndex = c - (config.LeftHeaderStartCol + config.LeftHeaderWidth);
                
                if (topIndex < 0 || topIndex >= topAxisKeys.Count) continue;

                string topKey = topAxisKeys[topIndex]; 
                string val = rowVals[c];
                
                if (string.IsNullOrWhiteSpace(val)) continue; // Sparse

                // C. Construct Final Key
                string fullKey = $"{sheetName}:{leftKey}*{topKey}";
                
                await storage.SetAsync(fullKey, val);

                // D. Live Compute
                if (LiveAggregator.IsMetric(topKey) && double.TryParse(val, out double dVal))
                {
                     await storage.IncrementAsync($"Stats:Global:{topKey}", dVal);
                }
            }
            processedCount++;
        }
        
        return processedCount;
    }

    private static string[] FlattenDictionaryRow(IDictionary<string, object> rowDict)
    {
        // MiniExcel Dynamic Dictionary Keys are A, B... AA..
        // We assume we want 0-indexed string array.
        // We find the 'Max' column index to allocate array.
        
        // This sorting + re-indexing is a bit naive for very wide sheets but OK for PoC.
        // Better to use MiniExcel's column index if available, but dynamic object hides it.
        // We'll trust the Key sorting for now.
        var sortedKeys = rowDict.Keys.OrderBy(k => k.Length).ThenBy(k => k).ToList();
        var result = new string[sortedKeys.Count]; 
        // Note: Dictionary might define "A", "C" but skip "B". 
        // This simple list approach collapses them. 
        // TO BE EXACT: We should convert "A"->0, "B"->1.
        // For PoC we keep this, but in production we need ColumnLetterToIndex logic.
        
        for (int i = 0; i < sortedKeys.Count; i++)
        {
            var val = rowDict[sortedKeys[i]];
            result[i] = val?.ToString() ?? "";
        }
        return result;
    }

    private static List<string> FlattenTopHeaders(List<string[]> headerRows, int startCol)
    {
        if (headerRows.Count == 0) return new List<string>();
        int maxCol = headerRows.Max(r => r.Length);
        var flatHeaders = new List<string>();
        
        var lastValues = new string[headerRows.Count]; // Last value for each ROW level (Horizontal Fill)

        // Iterate Columns
        for (int c = startCol; c < maxCol; c++)
        {
            var parts = new List<string>();
            // Iterate Rows (Depth)
            for (int r = 0; r < headerRows.Count; r++)
            {
                string val = (c < headerRows[r].Length) ? headerRows[r][c] : "";
                
                // Horizontal Forward Fill (Unmerge Logic)
                if (string.IsNullOrWhiteSpace(val))
                {
                    val = lastValues[r];
                }
                else
                {
                    lastValues[r] = val;
                }
                
                if (!string.IsNullOrWhiteSpace(val)) parts.Add(val);
            }
            flatHeaders.Add(string.Join(".", parts));
        }
        return flatHeaders;
    }
}