using System.IO;
using System.Text;
using System.Text.Json;
using Microsoft.Data.Sqlite;

namespace AxCopilot.Services.Agent;

/// <summary>
/// SQLite 데이터베이스 쿼리 실행 도구.
/// 로컬 .db/.sqlite 파일에 대해 SELECT/INSERT/UPDATE/DELETE 쿼리를 실행합니다.
/// </summary>
public class SqlTool : IAgentTool
{
    public string Name => "sql_tool";
    public string Description =>
        "Execute SQL queries on local SQLite database files. Actions: " +
        "'query' — run SELECT query and return results as table; " +
        "'execute' — run INSERT/UPDATE/DELETE and return affected rows; " +
        "'schema' — show database schema (tables, columns, types); " +
        "'tables' — list all tables in the database.";

    public ToolParameterSchema Parameters => new()
    {
        Properties = new()
        {
            ["action"] = new()
            {
                Type = "string",
                Description = "Action to perform",
                Enum = ["query", "execute", "schema", "tables"],
            },
            ["db_path"] = new()
            {
                Type = "string",
                Description = "Path to SQLite database file (.db, .sqlite, .sqlite3)",
            },
            ["sql"] = new()
            {
                Type = "string",
                Description = "SQL query to execute (for query/execute actions)",
            },
            ["max_rows"] = new()
            {
                Type = "string",
                Description = "Maximum rows to return (default: 100, max: 1000)",
            },
        },
        Required = ["action", "db_path"],
    };

    public Task<ToolResult> ExecuteAsync(JsonElement args, AgentContext context, CancellationToken ct = default)
    {
        var action = args.GetProperty("action").GetString() ?? "";
        var dbPath = args.GetProperty("db_path").GetString() ?? "";

        if (!Path.IsPathRooted(dbPath))
            dbPath = Path.Combine(context.WorkFolder, dbPath);

        if (!File.Exists(dbPath))
            return Task.FromResult(ToolResult.Fail($"Database file not found: {dbPath}"));

        try
        {
            var connStr = $"Data Source={dbPath};Mode=ReadOnly";
            // execute 액션은 ReadWrite 필요
            if (action == "execute")
                connStr = $"Data Source={dbPath}";

            using var conn = new SqliteConnection(connStr);
            conn.Open();

            return Task.FromResult(action switch
            {
                "query"   => QueryAction(conn, args),
                "execute" => ExecuteAction(conn, args),
                "schema"  => SchemaAction(conn),
                "tables"  => TablesAction(conn),
                _         => ToolResult.Fail($"Unknown action: {action}"),
            });
        }
        catch (Exception ex)
        {
            return Task.FromResult(ToolResult.Fail($"SQL 오류: {ex.Message}"));
        }
    }

    private static ToolResult QueryAction(SqliteConnection conn, JsonElement args)
    {
        if (!args.TryGetProperty("sql", out var sqlProp))
            return ToolResult.Fail("'sql' parameter is required for query action");

        var sql = sqlProp.GetString() ?? "";

        // SELECT만 허용
        if (!sql.TrimStart().StartsWith("SELECT", StringComparison.OrdinalIgnoreCase) &&
            !sql.TrimStart().StartsWith("WITH", StringComparison.OrdinalIgnoreCase) &&
            !sql.TrimStart().StartsWith("PRAGMA", StringComparison.OrdinalIgnoreCase))
            return ToolResult.Fail("Query action only allows SELECT/WITH/PRAGMA statements. Use 'execute' for modifications.");

        var maxRows = args.TryGetProperty("max_rows", out var mr) && int.TryParse(mr.GetString(), out var mrv)
            ? Math.Min(mrv, 1000) : 100;

        using var cmd = conn.CreateCommand();
        cmd.CommandText = sql;

        using var reader = cmd.ExecuteReader();
        var sb = new StringBuilder();
        var colCount = reader.FieldCount;

        // 헤더
        var colNames = new string[colCount];
        for (var i = 0; i < colCount; i++)
            colNames[i] = reader.GetName(i);
        sb.AppendLine(string.Join(" | ", colNames));
        sb.AppendLine(new string('-', colNames.Sum(c => c.Length + 3)));

        // 행
        var rowCount = 0;
        while (reader.Read() && rowCount < maxRows)
        {
            var values = new string[colCount];
            for (var i = 0; i < colCount; i++)
                values[i] = reader.IsDBNull(i) ? "NULL" : reader.GetValue(i)?.ToString() ?? "";
            sb.AppendLine(string.Join(" | ", values));
            rowCount++;
        }

        if (rowCount == 0)
            return ToolResult.Ok("Query returned 0 rows.");

        var result = sb.ToString();
        if (result.Length > 8000) result = result[..8000] + "\n... (truncated)";
        return ToolResult.Ok($"Rows: {rowCount}" + (rowCount >= maxRows ? $" (limited to {maxRows})" : "") + $"\n\n{result}");
    }

    private static ToolResult ExecuteAction(SqliteConnection conn, JsonElement args)
    {
        if (!args.TryGetProperty("sql", out var sqlProp))
            return ToolResult.Fail("'sql' parameter is required for execute action");

        var sql = sqlProp.GetString() ?? "";

        // DDL/DML만 허용 (DROP DATABASE 등 위험 명령 차단)
        var trimmed = sql.TrimStart().ToUpperInvariant();
        if (trimmed.StartsWith("DROP DATABASE") || trimmed.StartsWith("ATTACH") || trimmed.StartsWith("DETACH"))
            return ToolResult.Fail("Security: DROP DATABASE, ATTACH, DETACH are not allowed.");

        using var cmd = conn.CreateCommand();
        cmd.CommandText = sql;
        var affected = cmd.ExecuteNonQuery();
        return ToolResult.Ok($"✓ {affected} row(s) affected");
    }

    private static ToolResult SchemaAction(SqliteConnection conn)
    {
        var sb = new StringBuilder();
        using var cmd = conn.CreateCommand();
        cmd.CommandText = "SELECT name FROM sqlite_master WHERE type='table' ORDER BY name";
        using var reader = cmd.ExecuteReader();

        var tables = new List<string>();
        while (reader.Read()) tables.Add(reader.GetString(0));
        reader.Close();

        foreach (var table in tables)
        {
            sb.AppendLine($"## {table}");
            using var pragmaCmd = conn.CreateCommand();
            pragmaCmd.CommandText = $"PRAGMA table_info(\"{table}\")";
            using var pragmaReader = pragmaCmd.ExecuteReader();
            sb.AppendLine($"{"#",-4} {"Name",-25} {"Type",-15} {"NotNull",-8} {"Default",-15} {"PK"}");
            while (pragmaReader.Read())
            {
                sb.AppendLine($"{pragmaReader.GetInt32(0),-4} " +
                    $"{pragmaReader.GetString(1),-25} " +
                    $"{pragmaReader.GetString(2),-15} " +
                    $"{(pragmaReader.GetInt32(3) == 1 ? "YES" : ""),-8} " +
                    $"{(pragmaReader.IsDBNull(4) ? "" : pragmaReader.GetString(4)),-15} " +
                    $"{(pragmaReader.GetInt32(5) > 0 ? "PK" : "")}");
            }
            pragmaReader.Close();
            sb.AppendLine();
        }

        return ToolResult.Ok(sb.ToString());
    }

    private static ToolResult TablesAction(SqliteConnection conn)
    {
        using var cmd = conn.CreateCommand();
        cmd.CommandText = @"
            SELECT m.name, m.type,
                   (SELECT count(*) FROM pragma_table_info(m.name)) as col_count
            FROM sqlite_master m
            WHERE m.type IN ('table','view')
            ORDER BY m.type, m.name";
        using var reader = cmd.ExecuteReader();

        var sb = new StringBuilder();
        sb.AppendLine($"{"Name",-30} {"Type",-8} {"Columns"}");
        sb.AppendLine(new string('-', 50));
        var count = 0;
        while (reader.Read())
        {
            sb.AppendLine($"{reader.GetString(0),-30} {reader.GetString(1),-8} {reader.GetInt32(2)}");
            count++;
        }
        return ToolResult.Ok($"Found {count} tables/views:\n\n{sb}");
    }
}