using System;
using System.Collections.Generic;
using System.Threading.Tasks;
using Dapper;
using Gott.Extensions;
using Gott.Services;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Http;
using Microsoft.Data.Sqlite;

namespace Gott.Endpoints;

public static class DatabaseExplorerEndpoint
{
    public static void MapDatabaseExplorerEndpoints(this WebApplication app)
    {
        app.MapGet("/api/admin/db/tables", HandleGetTables);
        app.MapGet("/api/admin/db/tables/{name}", HandleGetTableData);
    }

    private static async Task HandleGetTables(HttpContext ctx, DatabaseService db)
    {
        if (!ctx.IsAdmin())
        {
            ctx.Response.StatusCode = 403;
            await ctx.Response.WriteAsJsonAsync(new { error = "Admin access required" });
            return;
        }

        using var conn = db.GetConnection();
        var tables = conn.Query<TableInfo>(
            "SELECT name, (SELECT COUNT(*) FROM pragma_table_info(m.name)) as column_count " +
            "FROM sqlite_master m WHERE type = 'table' AND name NOT LIKE 'sqlite_%' ORDER BY name");

        var result = new List<object>();
        foreach (var t in tables)
        {
            var rowCount = conn.ExecuteScalar<long>($"SELECT COUNT(*) FROM \"{t.Name}\"");
            result.Add(new { name = t.Name, columns = t.ColumnCount, rows = rowCount });
        }

        await ctx.Response.WriteAsJsonAsync(new { tables = result });
    }

    private static async Task HandleGetTableData(HttpContext ctx, DatabaseService db, string name)
    {
        if (!ctx.IsAdmin())
        {
            ctx.Response.StatusCode = 403;
            await ctx.Response.WriteAsJsonAsync(new { error = "Admin access required" });
            return;
        }

        // Tabellennamen validieren (SQL-Injection verhindern)
        using var conn = db.GetConnection();
        var exists = conn.ExecuteScalar<int>(
            "SELECT COUNT(*) FROM sqlite_master WHERE type = 'table' AND name = @name",
            new { name });

        if (exists == 0)
        {
            ctx.Response.StatusCode = 404;
            await ctx.Response.WriteAsJsonAsync(new { error = "Table not found" });
            return;
        }

        // Pagination
        var page = 1;
        var pageSize = 1000;
        if (ctx.Request.Query.TryGetValue("page", out var pageStr) && int.TryParse(pageStr, out var p) && p > 0)
            page = p;
        if (ctx.Request.Query.TryGetValue("pageSize", out var psStr) && int.TryParse(psStr, out var ps) && ps > 0 && ps <= 10000)
            pageSize = ps;

        var offset = (page - 1) * pageSize;

        // Spalten-Info
        var columns = conn.Query<ColumnInfo>($"PRAGMA table_info(\"{name}\")");

        // Daten
        var totalRows = conn.ExecuteScalar<long>($"SELECT COUNT(*) FROM \"{name}\"");
        var rows = conn.Query($"SELECT * FROM \"{name}\" LIMIT @limit OFFSET @offset",
            new { limit = pageSize, offset });

        await ctx.Response.WriteAsJsonAsync(new
        {
            table = name,
            columns,
            rows,
            pagination = new
            {
                page,
                pageSize,
                totalRows,
                totalPages = (int)Math.Ceiling((double)totalRows / pageSize)
            }
        });
    }

    private class TableInfo
    {
        public string Name { get; set; }
        public int ColumnCount { get; set; }
    }

    private class ColumnInfo
    {
        public int Cid { get; set; }
        public string Name { get; set; }
        public string Type { get; set; }
        public int Notnull { get; set; }
        public string DfltValue { get; set; }
        public int Pk { get; set; }
    }
}