using System;
using System.Collections.Generic;
using System.Runtime.Serialization;
using System.Text;
using Npgsql.BackendMessages;
using Npgsql.Internal;

namespace Npgsql;

/// <summary>
/// The exception that is thrown when the PostgreSQL backend reports errors (e.g. query
/// SQL issues, constraint violations).
/// </summary>
/// <remarks>
/// This exception only corresponds to a PostgreSQL-delivered error.
/// Other errors (e.g. network issues) will be raised via <see cref="NpgsqlException" />,
/// and purely Npgsql-related issues which aren't related to the server will be raised
/// via the standard CLR exceptions (e.g. <see cref="ArgumentException" />).
///
/// See https://www.postgresql.org/docs/current/static/errcodes-appendix.html,
/// https://www.postgresql.org/docs/current/static/protocol-error-fields.html
/// </remarks>
[Serializable]
public sealed class PostgresException : NpgsqlException
{
    /// <summary>
    /// Creates a new instance.
    /// </summary>
    public PostgresException(string messageText, string severity, string invariantSeverity, string sqlState)
        : this(messageText, severity, invariantSeverity, sqlState, detail: null) {}

    /// <summary>
    /// Creates a new instance.
    /// </summary>
    public PostgresException(
        string messageText, string severity, string invariantSeverity, string sqlState,
        string? detail = null, string? hint = null, int position = 0, int internalPosition = 0,
        string? internalQuery = null, string? where = null, string? schemaName = null, string? tableName = null,
        string? columnName = null, string? dataTypeName = null, string? constraintName = null, string? file = null,
        string? line = null, string? routine = null)
        : base(GetMessage(sqlState, messageText, position, detail))
    {
        MessageText = messageText;
        Severity = severity;
        InvariantSeverity = invariantSeverity;
        SqlState = sqlState;

        Detail = detail;
        Hint = hint;
        Position = position;
        InternalPosition = internalPosition;
        InternalQuery = internalQuery;
        Where = where;
        SchemaName = schemaName;
        TableName = tableName;
        ColumnName = columnName;
        DataTypeName = dataTypeName;
        ConstraintName = constraintName;
        File = file;
        Line = line;
        Routine = routine;

        AddData(nameof(Severity), Severity);
        AddData(nameof(InvariantSeverity), InvariantSeverity);
        AddData(nameof(SqlState), SqlState);
        AddData(nameof(MessageText), MessageText);
        AddData(nameof(Detail), Detail);
        AddData(nameof(Hint), Hint);
        AddData(nameof(Position), Position);
        AddData(nameof(InternalPosition), InternalPosition);
        AddData(nameof(InternalQuery), InternalQuery);
        AddData(nameof(Where), Where);
        AddData(nameof(SchemaName), SchemaName);
        AddData(nameof(TableName), TableName);
        AddData(nameof(ColumnName), ColumnName);
        AddData(nameof(DataTypeName), DataTypeName);
        AddData(nameof(ConstraintName), ConstraintName);
        AddData(nameof(File), File);
        AddData(nameof(Line), Line);
        AddData(nameof(Routine), Routine);

        void AddData<T>(string key, T value)
        {
            if (!EqualityComparer<T>.Default.Equals(value, default!))
                Data.Add(key, value);
        }
    }

    static string GetMessage(string sqlState, string messageText, int position, string? detail)
    {
        var baseMessage = sqlState + ": " + messageText;
        var additionalMessage =
            TryAddString("POSITION", position == 0 ? null : position.ToString()) +
            TryAddString("DETAIL", detail);
        return string.IsNullOrEmpty(additionalMessage)
            ? baseMessage
            : baseMessage + Environment.NewLine + additionalMessage;
    }

    static string TryAddString(string text, string? value) => !string.IsNullOrWhiteSpace(value) ? $"{Environment.NewLine}{text}: {value}" : string.Empty;

    PostgresException(ErrorOrNoticeMessage msg)
        : this(
            msg.Message, msg.Severity, msg.InvariantSeverity, msg.SqlState,
            msg.Detail, msg.Hint, msg.Position, msg.InternalPosition, msg.InternalQuery,
            msg.Where, msg.SchemaName, msg.TableName, msg.ColumnName, msg.DataTypeName,
            msg.ConstraintName, msg.File, msg.Line, msg.Routine) {}

    internal static PostgresException Load(NpgsqlReadBuffer buf, bool includeDetail)
        => new(ErrorOrNoticeMessage.Load(buf, includeDetail));

    internal PostgresException(SerializationInfo info, StreamingContext context)
        : base(info, context)
    {
        Severity = GetValue<string>(nameof(Severity));
        InvariantSeverity = GetValue<string>(nameof(InvariantSeverity));
        SqlState = GetValue<string>(nameof(SqlState));
        MessageText = GetValue<string>(nameof(MessageText));
        Detail = GetValue<string>(nameof(Detail));
        Hint = GetValue<string>(nameof(Hint));
        Position = GetValue<int>(nameof(Position));
        InternalPosition = GetValue<int>(nameof(InternalPosition));
        InternalQuery = GetValue<string>(nameof(InternalQuery));
        Where = GetValue<string>(nameof(Where));
        SchemaName = GetValue<string>(nameof(SchemaName));
        TableName = GetValue<string>(nameof(TableName));
        ColumnName = GetValue<string>(nameof(ColumnName));
        DataTypeName = GetValue<string>(nameof(DataTypeName));
        ConstraintName = GetValue<string>(nameof(ConstraintName));
        File = GetValue<string>(nameof(File));
        Line = GetValue<string>(nameof(Line));
        Routine = GetValue<string>(nameof(Routine));

        T GetValue<T>(string propertyName) => (T)info.GetValue(propertyName, typeof(T))!;
    }

    /// <summary>
    /// Populates a <see cref="SerializationInfo"/> with the data needed to serialize the target object.
    /// </summary>
    /// <param name="info">The <see cref="SerializationInfo"/> to populate with data.</param>
    /// <param name="context">The destination (see <see cref="StreamingContext"/>) for this serialization.</param>
    public override void GetObjectData(SerializationInfo info, StreamingContext context)
    {
        base.GetObjectData(info, context);
        info.AddValue(nameof(Severity), Severity);
        info.AddValue(nameof(InvariantSeverity), InvariantSeverity);
        info.AddValue(nameof(SqlState), SqlState);
        info.AddValue(nameof(MessageText), MessageText);
        info.AddValue(nameof(Detail), Detail);
        info.AddValue(nameof(Hint), Hint);
        info.AddValue(nameof(Position), Position);
        info.AddValue(nameof(InternalPosition), InternalPosition);
        info.AddValue(nameof(InternalQuery), InternalQuery);
        info.AddValue(nameof(Where), Where);
        info.AddValue(nameof(SchemaName), SchemaName);
        info.AddValue(nameof(TableName), TableName);
        info.AddValue(nameof(ColumnName), ColumnName);
        info.AddValue(nameof(DataTypeName), DataTypeName);
        info.AddValue(nameof(ConstraintName), ConstraintName);
        info.AddValue(nameof(File), File);
        info.AddValue(nameof(Line), Line);
        info.AddValue(nameof(Routine), Routine);
    }

    /// <inheritdoc />
    public override string ToString()
    {
        var builder = new StringBuilder(base.ToString())
            .AppendLine().Append("  Exception data:");

        AppendLine(nameof(Severity), Severity);
        AppendLine(nameof(SqlState), SqlState);
        AppendLine(nameof(MessageText), MessageText);
        AppendLine(nameof(Detail), Detail);
        AppendLine(nameof(Hint), Hint);
        AppendLine(nameof(Position), Position);
        AppendLine(nameof(InternalPosition), InternalPosition);
        AppendLine(nameof(InternalQuery), InternalQuery);
        AppendLine(nameof(Where), Where);
        AppendLine(nameof(SchemaName), SchemaName);
        AppendLine(nameof(TableName), TableName);
        AppendLine(nameof(ColumnName), ColumnName);
        AppendLine(nameof(DataTypeName), DataTypeName);
        AppendLine(nameof(ConstraintName), ConstraintName);
        AppendLine(nameof(File), File);
        AppendLine(nameof(Line), Line);
        AppendLine(nameof(Routine), Routine);

        return builder.ToString();

        void AppendLine<T>(string propertyName, T propertyValue)
        {
            if (!EqualityComparer<T>.Default.Equals(propertyValue, default!))
                builder.AppendLine().Append("    ").Append(propertyName).Append(": ").Append(propertyValue);
        }
    }

    /// <summary>
    /// Specifies whether the exception is considered transient, that is, whether retrying the operation could
    /// succeed (e.g. a network error). Check <see cref="SqlState"/>.
    /// </summary>
    public override bool IsTransient
    {
        get
        {
            switch (SqlState)
            {
            case PostgresErrorCodes.InsufficientResources:
            case PostgresErrorCodes.DiskFull:
            case PostgresErrorCodes.OutOfMemory:
            case PostgresErrorCodes.TooManyConnections:
            case PostgresErrorCodes.ConfigurationLimitExceeded:
            case PostgresErrorCodes.CannotConnectNow:
            case PostgresErrorCodes.SystemError:
            case PostgresErrorCodes.IoError:
            case PostgresErrorCodes.SerializationFailure:
            case PostgresErrorCodes.DeadlockDetected:
            case PostgresErrorCodes.LockNotAvailable:
            case PostgresErrorCodes.ObjectInUse:
            case PostgresErrorCodes.ObjectNotInPrerequisiteState:
            case PostgresErrorCodes.ConnectionException:
            case PostgresErrorCodes.ConnectionDoesNotExist:
            case PostgresErrorCodes.ConnectionFailure:
            case PostgresErrorCodes.SqlClientUnableToEstablishSqlConnection:
            case PostgresErrorCodes.SqlServerRejectedEstablishmentOfSqlConnection:
            case PostgresErrorCodes.TransactionResolutionUnknown:
                return true;
            default:
                return false;
            }
        }
    }

    #region Message Fields

    /// <summary>
    /// Severity of the error or notice.
    /// Always present.
    /// </summary>
    public string Severity { get; }

    /// <summary>
    /// Severity of the error or notice, not localized.
    /// Always present since PostgreSQL 9.6.
    /// </summary>
    public string InvariantSeverity { get; }

    /// <summary>
    /// The SQLSTATE code for the error.
    /// </summary>
    /// <remarks>
    /// Always present.
    /// Constants are defined in <seealso cref="PostgresErrorCodes"/>.
    /// See https://www.postgresql.org/docs/current/static/errcodes-appendix.html
    /// </remarks>
#if NET5_0_OR_GREATER
    public override string SqlState { get; }
#else
        public string SqlState { get; }
#endif

    /// <summary>
    /// The SQLSTATE code for the error.
    /// </summary>
    /// <remarks>
    /// Always present.
    /// Constants are defined in <seealso cref="PostgresErrorCodes"/>.
    /// See https://www.postgresql.org/docs/current/static/errcodes-appendix.html
    /// </remarks>
    [Obsolete("Use SqlState instead")]
    public string Code => SqlState;

    /// <summary>
    /// The primary human-readable error message. This should be accurate but terse.
    /// </summary>
    /// <remarks>
    /// Always present.
    /// </remarks>
    public string MessageText { get; }

    /// <summary>
    /// An optional secondary error message carrying more detail about the problem.
    /// May run to multiple lines.
    /// </summary>
    public string? Detail { get; }

    /// <summary>
    /// An optional suggestion what to do about the problem.
    /// This is intended to differ from Detail in that it offers advice (potentially inappropriate) rather than hard facts.
    /// May run to multiple lines.
    /// </summary>
    public string? Hint { get; }

    /// <summary>
    /// The field value is a decimal ASCII integer, indicating an error cursor position as an index into the original query string.
    /// The first character has index 1, and positions are measured in characters not bytes.
    /// 0 means not provided.
    /// </summary>
    public int Position { get; }

    /// <summary>
    /// This is defined the same as the <see cref="Position"/> field, but it is used when the cursor position refers to an internally generated command rather than the one submitted by the client.
    /// The <see cref="InternalQuery" /> field will always appear when this field appears.
    /// 0 means not provided.
    /// </summary>
    public int InternalPosition { get; }

    /// <summary>
    /// The text of a failed internally-generated command.
    /// This could be, for example, a SQL query issued by a PL/pgSQL function.
    /// </summary>
    public string? InternalQuery { get; }

    /// <summary>
    /// An indication of the context in which the error occurred.
    /// Presently this includes a call stack traceback of active PL functions.
    /// The trace is one entry per line, most recent first.
    /// </summary>
    public string? Where { get; }

    /// <summary>
    /// If the error was associated with a specific database object, the name of the schema containing that object, if any.
    /// </summary>
    /// <remarks>PostgreSQL 9.3 and up.</remarks>
    public string? SchemaName { get; }

    /// <summary>
    /// Table name: if the error was associated with a specific table, the name of the table.
    /// (Refer to the schema name field for the name of the table's schema.)
    /// </summary>
    /// <remarks>PostgreSQL 9.3 and up.</remarks>
    public string? TableName { get; }

    /// <summary>
    /// If the error was associated with a specific table column, the name of the column.
    /// (Refer to the schema and table name fields to identify the table.)
    /// </summary>
    /// <remarks>PostgreSQL 9.3 and up.</remarks>
    public string? ColumnName { get; }

    /// <summary>
    /// If the error was associated with a specific data type, the name of the data type.
    /// (Refer to the schema name field for the name of the data type's schema.)
    /// </summary>
    /// <remarks>PostgreSQL 9.3 and up.</remarks>
    public string? DataTypeName { get; }

    /// <summary>
    /// If the error was associated with a specific constraint, the name of the constraint.
    /// Refer to fields listed above for the associated table or domain.
    /// (For this purpose, indexes are treated as constraints, even if they weren't created with constraint syntax.)
    /// </summary>
    /// <remarks>PostgreSQL 9.3 and up.</remarks>
    public string? ConstraintName { get; }

    /// <summary>
    /// The file name of the source-code location where the error was reported.
    /// </summary>
    /// <remarks>PostgreSQL 9.3 and up.</remarks>
    public string? File { get; }

    /// <summary>
    /// The line number of the source-code location where the error was reported.
    /// </summary>
    public string? Line { get; }

    /// <summary>
    /// The name of the source-code routine reporting the error.
    /// </summary>
    public string? Routine { get; }

    #endregion
}