using System.Text;
using System.Text.RegularExpressions;
using Admin.NET.Plugin.AiDOP.DataPlatform;
using Microsoft.Extensions.Logging;

namespace Admin.NET.Plugin.AiDOP.DataPlatform.Schema;

/// <summary>
/// 中台表（mdp_std_* / mdp_stg_* / dwd_*）的增量对齐。
/// 表不存在则按声明建表；已存在则只 ADD COLUMN / ADD KEY。不 DROP、不改类型、不改已有索引。
/// </summary>
public static class MdpSchemaAligner
{
    private static readonly Regex CreateHead = new(
        @"^CREATE\s+TABLE\s+IF\s+NOT\s+EXISTS\s+`?(?<name>[A-Za-z0-9_]+)`?(?:\s+LIKE\s+`?(?<like>[A-Za-z0-9_]+)`?)?",
        RegexOptions.IgnoreCase | RegexOptions.Compiled | RegexOptions.Singleline);

    private static readonly Regex IndexHead = new(
        @"^(?<unique>UNIQUE\s+)?(?:KEY|INDEX)\s+`?(?<name>[A-Za-z0-9_]+)`?\s*\((?<cols>[^)]+)\)",
        RegexOptions.IgnoreCase | RegexOptions.Compiled);

    public static bool IsNeutralTable(string name) =>
        name.StartsWith("mdp_std_", StringComparison.OrdinalIgnoreCase)
        || name.StartsWith("mdp_stg_", StringComparison.OrdinalIgnoreCase)
        || name.StartsWith("dwd_", StringComparison.OrdinalIgnoreCase);

    /// <summary>
    /// 非中立建表语句原样交给数据库；中立建表改为增量对齐，避免 CREATE IF NOT EXISTS 在表已存在时不补列。
    /// </summary>
    public static async Task<int> ExecuteAsync(ISqlSugarClient db, string sql, params SugarParameter[] parameters)
    {
        if (!ContainsNeutralCreate(sql))
            return await db.Ado.ExecuteCommandAsync(sql, parameters);

        var applied = 0;
        foreach (var statement in SplitStatements(sql))
        {
            if (IsNeutralCreate(statement))
                applied += await AlignOneAsync(db, statement);
            else
                applied += await db.Ado.ExecuteCommandAsync(statement, parameters);
        }
        return applied;
    }

    public static Task<int> ExecuteAsync(ISqlSugarClient db, string sql, List<SugarParameter> parameters) =>
        ExecuteAsync(db, sql, parameters?.ToArray() ?? []);

    public static async Task EnsureWrittenByColumnAsync(ISqlSugarClient db, string table)
    {
        if (!IsSafeName(table))
            throw new InvalidOperationException($"非法表名：{table}");
        var hasWritten = await db.Ado.GetIntAsync(
            """
            SELECT COUNT(*) FROM information_schema.COLUMNS
            WHERE TABLE_SCHEMA=DATABASE() AND TABLE_NAME=@t AND COLUMN_NAME='written_by'
            """,
            new SugarParameter("@t", table));
        if (hasWritten > 0) return;
        var ddl =
            $"ALTER TABLE `{table}` ADD COLUMN written_by VARCHAR(32) NOT NULL DEFAULT 'LEGACY_UNVERIFIED' COMMENT 'DB_SYNC/API_INBOUND/PLATFORM_FORM/SEED/LEGACY_UNVERIFIED'";
        await db.Ado.ExecuteCommandAsync(ddl);
        Log(ddl);
    }

    /// <summary>
    /// 给已有 source_system 的 mdp_std_* 补 written_by，并按贴源表名登记真实来源。
    /// 确证不了的行不改 source_system，只保持 written_by=LEGACY_UNVERIFIED。
    /// </summary>
    public static async Task EnsureSourceIdentityAsync(ISqlSugarClient db)
    {
        await db.Ado.ExecuteCommandAsync(
            """
            CREATE TABLE IF NOT EXISTS mdp_source_table_registry (
                id BIGINT NOT NULL AUTO_INCREMENT,
                source_table VARCHAR(64) NOT NULL COMMENT '贴源记录的原始表名',
                source_system VARCHAR(50) NOT NULL COMMENT '真实来源系统码',
                remark VARCHAR(255) NULL,
                PRIMARY KEY (id),
                UNIQUE KEY uk_source_table (source_table)
            ) COMMENT='原始表名 → 真实来源系统 的唯一对照'
            """);

        var stgTables = await db.Ado.SqlQueryAsync<NameRow>(
            """
            SELECT TABLE_NAME AS Name FROM information_schema.TABLES
            WHERE TABLE_SCHEMA = DATABASE() AND TABLE_NAME LIKE 'mdp_stg%'
            """);
        foreach (var table in stgTables)
        {
            if (!IsSafeName(table.Name)) continue;
            var hasSourceTable = await db.Ado.GetIntAsync(
                """
                SELECT COUNT(*) FROM information_schema.COLUMNS
                WHERE TABLE_SCHEMA=DATABASE() AND TABLE_NAME=@t AND COLUMN_NAME='source_table'
                """,
                new SugarParameter("@t", table.Name));
            if (hasSourceTable == 0) continue;

            var names = await db.Ado.SqlQueryAsync<NameRow>(
                $"SELECT DISTINCT source_table AS Name FROM `{table.Name}` WHERE source_table IS NOT NULL AND TRIM(source_table)<>''");
            foreach (var row in names)
            {
                var system = MdpSourceIdentity.ClassifySourceTable(row.Name);
                if (system == null)
                {
                    Log($"来源表未登记（命名规则无法确证，不猜测）: {row.Name}");
                    continue;
                }

                await db.Ado.ExecuteCommandAsync(
                    """
                    INSERT INTO mdp_source_table_registry (source_table, source_system, remark)
                    SELECT @t, @s, '1.0.565 按表名规则登记'
                    FROM DUAL
                    WHERE NOT EXISTS (SELECT 1 FROM mdp_source_table_registry WHERE source_table=@t)
                    """,
                    new SugarParameter("@t", row.Name.Trim()),
                    new SugarParameter("@s", system));
            }
        }

        var stdTables = await db.Ado.SqlQueryAsync<NameRow>(
            """
            SELECT TABLE_NAME AS Name FROM information_schema.COLUMNS
            WHERE TABLE_SCHEMA=DATABASE() AND COLUMN_NAME='source_system' AND TABLE_NAME LIKE 'mdp_std%'
            """);
        foreach (var table in stdTables.Select(t => t.Name).Distinct(StringComparer.OrdinalIgnoreCase))
        {
            if (!IsSafeName(table)) continue;
            var hasWritten = await db.Ado.GetIntAsync(
                """
                SELECT COUNT(*) FROM information_schema.COLUMNS
                WHERE TABLE_SCHEMA=DATABASE() AND TABLE_NAME=@t AND COLUMN_NAME='written_by'
                """,
                new SugarParameter("@t", table));
            if (hasWritten == 0)
            {
                var ddl =
                    $"ALTER TABLE `{table}` ADD COLUMN written_by VARCHAR(32) NOT NULL DEFAULT 'LEGACY_UNVERIFIED' COMMENT 'DB_SYNC/API_INBOUND/PLATFORM_FORM/SEED/LEGACY_UNVERIFIED'";
                await db.Ado.ExecuteCommandAsync(ddl);
                Log(ddl);
            }

            var defaults = await db.Ado.SqlQueryAsync<NameRow>(
                """
                SELECT COLUMN_DEFAULT AS Name FROM information_schema.COLUMNS
                WHERE TABLE_SCHEMA=DATABASE() AND TABLE_NAME=@t AND COLUMN_NAME='source_system'
                """,
                new SugarParameter("@t", table));
            var currentDefault = defaults.FirstOrDefault()?.Name?.Trim().Trim('\'') ?? "";
            if (currentDefault == "AIDOP")
            {
                var ddl = $"ALTER TABLE `{table}` ALTER COLUMN source_system SET DEFAULT ''";
                await db.Ado.ExecuteCommandAsync(ddl);
                Log(ddl);
            }

            await db.Ado.ExecuteCommandAsync(
                $"""
                UPDATE `{table}` SET written_by='DB_SYNC'
                WHERE written_by='LEGACY_UNVERIFIED'
                  AND source_system IN ('DOPDEMORQ_SQLSERVER','T8','AIDOPDEV_MYSQL')
                """);
            await db.Ado.ExecuteCommandAsync(
                $"""
                UPDATE `{table}` SET written_by='SEED'
                WHERE written_by='LEGACY_UNVERIFIED'
                  AND source_system IN ('UAT_GENERATOR','UAT','DEMO')
                """);
            await db.Ado.ExecuteCommandAsync(
                $"""
                UPDATE `{table}` SET written_by='API_INBOUND'
                WHERE written_by='LEGACY_UNVERIFIED' AND source_system='API'
                """);
            await db.Ado.ExecuteCommandAsync(
                $"""
                UPDATE `{table}` SET written_by='PLATFORM_FORM'
                WHERE written_by='LEGACY_UNVERIFIED' AND source_system='AIDOP_NATIVE'
                """);
        }

        await BackfillProvenSourceAsync(db, stdTables.Select(t => t.Name).Distinct(StringComparer.OrdinalIgnoreCase));
    }

    private static async Task BackfillProvenSourceAsync(ISqlSugarClient db, IEnumerable<string> stdTables)
    {
        var stg = await db.Ado.SqlQueryAsync<NameRow>(
            """
            SELECT c.TABLE_NAME AS Name
            FROM information_schema.COLUMNS c
            WHERE c.TABLE_SCHEMA=DATABASE() AND c.TABLE_NAME LIKE 'mdp_stg%' AND c.COLUMN_NAME='source_biz_key'
              AND EXISTS (
                SELECT 1 FROM information_schema.COLUMNS t
                WHERE t.TABLE_SCHEMA=DATABASE() AND t.TABLE_NAME=c.TABLE_NAME AND t.COLUMN_NAME='source_table')
              AND EXISTS (
                SELECT 1 FROM information_schema.COLUMNS t
                WHERE t.TABLE_SCHEMA=DATABASE() AND t.TABLE_NAME=c.TABLE_NAME AND t.COLUMN_NAME='tenant_id')
            """);
        var stgNames = stg.Select(x => x.Name).Where(IsSafeName).Distinct(StringComparer.OrdinalIgnoreCase).ToList();
        if (stgNames.Count == 0) return;

        var union = string.Join(" UNION ALL ", stgNames.Select(n =>
            $"SELECT g.tenant_id, g.source_biz_key, r.source_system FROM `{n}` g JOIN mdp_source_table_registry r ON r.source_table=g.source_table"));
        var proven =
            $"""
            SELECT tenant_id, source_biz_key, MIN(source_system) AS source_system
            FROM ({union}) u
            GROUP BY tenant_id, source_biz_key
            HAVING COUNT(DISTINCT source_system)=1
            """;

        foreach (var table in stdTables)
        {
            if (!IsSafeName(table)) continue;
            var ready = await db.Ado.GetIntAsync(
                """
                SELECT COUNT(*) FROM information_schema.COLUMNS
                WHERE TABLE_SCHEMA=DATABASE() AND TABLE_NAME=@t
                  AND COLUMN_NAME IN ('tenant_id','source_biz_key','source_system','written_by','id')
                """,
                new SugarParameter("@t", table));
            if (ready < 5) continue;

            try
            {
                await db.Ado.ExecuteCommandAsync(
                    $"""
                    UPDATE `{table}` s
                    JOIN ({proven}) x ON x.tenant_id=s.tenant_id AND x.source_biz_key=s.source_biz_key
                    LEFT JOIN `{table}` o
                      ON o.tenant_id=s.tenant_id AND o.source_system=x.source_system
                     AND o.source_biz_key=s.source_biz_key AND o.id<>s.id
                    SET s.source_system=x.source_system, s.written_by='DB_SYNC'
                    WHERE s.source_system IN ('AIDOP','','AIDOP_LEGACY')
                      AND o.id IS NULL
                    """);
            }
            catch (Exception ex)
            {
                Log($"来源回填跳过 {table}: {ex.Message}");
            }
        }
    }

    private static bool IsSafeName(string? name) =>
        !string.IsNullOrWhiteSpace(name) && Regex.IsMatch(name, "^[A-Za-z0-9_]+$");

    public static IReadOnlyList<string> Plan(string statement, SchemaSnapshot snapshot)
    {
        var text = statement.Trim().TrimEnd(';').Trim();
        var head = CreateHead.Match(text);
        if (!head.Success || !IsNeutralTable(head.Groups["name"].Value))
            return [text];

        var table = head.Groups["name"].Value;
        if (head.Groups["like"].Success)
            return snapshot.Exists ? [] : [text];
        if (!snapshot.Exists)
            return [text];

        var alters = new List<string>();
        foreach (var part in SplitTopLevel(Body(text)))
        {
            var line = part.Trim().TrimEnd(',').Trim();
            if (line.Length == 0) continue;
            if (line.StartsWith("PRIMARY", StringComparison.OrdinalIgnoreCase)
                || line.StartsWith("CONSTRAINT", StringComparison.OrdinalIgnoreCase)
                || line.StartsWith("FULLTEXT", StringComparison.OrdinalIgnoreCase)
                || line.StartsWith("SPATIAL", StringComparison.OrdinalIgnoreCase))
                continue;

            var index = IndexHead.Match(line);
            if (index.Success)
            {
                var indexName = index.Groups["name"].Value;
                if (snapshot.Indexes.Contains(indexName)) continue;
                var unique = index.Groups["unique"].Success ? "UNIQUE KEY" : "KEY";
                alters.Add(
                    $"ALTER TABLE `{table}` ADD {unique} `{indexName}` ({index.Groups["cols"].Value.Trim()})");
                continue;
            }

            if (line.StartsWith("UNIQUE", StringComparison.OrdinalIgnoreCase)
                || line.StartsWith("KEY", StringComparison.OrdinalIgnoreCase)
                || line.StartsWith("INDEX", StringComparison.OrdinalIgnoreCase))
                continue;

            var column = ColumnName(line);
            if (column.Length == 0 || snapshot.Columns.Contains(column)) continue;
            alters.Add($"ALTER TABLE `{table}` ADD COLUMN {line}");
        }
        return alters;
    }

    private static async Task<int> AlignOneAsync(ISqlSugarClient db, string statement)
    {
        var head = CreateHead.Match(statement.Trim());
        var table = head.Groups["name"].Value;
        var snapshot = await LoadAsync(db, table);
        var planned = Plan(statement, snapshot);
        var applied = 0;
        foreach (var ddl in planned)
        {
            if (ddl.Contains("DROP ", StringComparison.OrdinalIgnoreCase))
                throw new InvalidOperationException("中台结构对齐器禁止执行 DROP");
            await db.Ado.ExecuteCommandAsync(ddl);
            Log(ddl);
            applied++;
        }
        return applied;
    }

    private static async Task<SchemaSnapshot> LoadAsync(ISqlSugarClient db, string table)
    {
        var exists = await db.Ado.GetIntAsync(
            """
            SELECT COUNT(*) FROM information_schema.TABLES
            WHERE TABLE_SCHEMA=DATABASE() AND TABLE_NAME=@t
            """,
            new SugarParameter("@t", table));
        if (exists == 0)
            return SchemaSnapshot.Missing;

        var columns = await db.Ado.SqlQueryAsync<NameRow>(
            """
            SELECT COLUMN_NAME AS Name FROM information_schema.COLUMNS
            WHERE TABLE_SCHEMA=DATABASE() AND TABLE_NAME=@t
            """,
            new SugarParameter("@t", table));
        var indexes = await db.Ado.SqlQueryAsync<NameRow>(
            """
            SELECT DISTINCT INDEX_NAME AS Name FROM information_schema.STATISTICS
            WHERE TABLE_SCHEMA=DATABASE() AND TABLE_NAME=@t
            """,
            new SugarParameter("@t", table));
        return new SchemaSnapshot(
            true,
            columns.Select(x => x.Name),
            indexes.Select(x => x.Name));
    }

    private static void Log(string ddl)
    {
        try
        {
            App.GetService<ILogger<MdpSchemaAlignerLog>>()?.LogInformation("中台结构对齐 {Ddl}", ddl);
        }
        catch
        {
            // 单测与未建容器时不记日志
        }
    }

    internal static bool ContainsNeutralCreate(string sql) =>
        SplitStatements(sql).Any(IsNeutralCreate);

    private static bool IsNeutralCreate(string statement)
    {
        var head = CreateHead.Match(statement.Trim());
        return head.Success && IsNeutralTable(head.Groups["name"].Value);
    }

    internal static List<string> SplitStatements(string sql)
    {
        var list = new List<string>();
        var sb = new StringBuilder();
        var depth = 0;
        var quote = false;
        for (var i = 0; i < sql.Length; i++)
        {
            var c = sql[i];
            if (c == '\'')
            {
                if (quote && i + 1 < sql.Length && sql[i + 1] == '\'')
                {
                    sb.Append("''");
                    i++;
                    continue;
                }
                quote = !quote;
                sb.Append(c);
                continue;
            }
            if (!quote && c == '(') depth++;
            if (!quote && c == ')' && depth > 0) depth--;
            if (!quote && depth == 0 && c == ';')
            {
                Add(list, sb);
                continue;
            }
            sb.Append(c);
        }
        Add(list, sb);
        return list;
    }

    private static void Add(List<string> list, StringBuilder sb)
    {
        var text = sb.ToString().Trim();
        if (text.Length > 0) list.Add(text);
        sb.Clear();
    }

    private static string Body(string create)
    {
        var start = create.IndexOf('(');
        var end = create.LastIndexOf(')');
        if (start < 0 || end <= start) return string.Empty;
        return create.Substring(start + 1, end - start - 1);
    }

    private static List<string> SplitTopLevel(string body)
    {
        var list = new List<string>();
        var sb = new StringBuilder();
        var depth = 0;
        var quote = false;
        foreach (var c in body)
        {
            if (c == '\'') quote = !quote;
            if (!quote && c == '(') depth++;
            if (!quote && c == ')' && depth > 0) depth--;
            if (!quote && depth == 0 && c == ',')
            {
                list.Add(sb.ToString());
                sb.Clear();
                continue;
            }
            sb.Append(c);
        }
        if (sb.Length > 0) list.Add(sb.ToString());
        return list;
    }

    private static string ColumnName(string line)
    {
        var token = line.Split([' ', '\t', '\r', '\n'], 2, StringSplitOptions.RemoveEmptyEntries)[0];
        return token.Trim('`');
    }

    private sealed class NameRow
    {
        public string Name { get; set; } = string.Empty;
    }

    /// <summary>仅用于取日志泛型，避免把静态类当作日志类别。</summary>
    private sealed class MdpSchemaAlignerLog;
}

public sealed class SchemaSnapshot
{
    public static readonly SchemaSnapshot Missing = new(false, [], []);

    public SchemaSnapshot(bool exists, IEnumerable<string> columns, IEnumerable<string> indexes)
    {
        Exists = exists;
        Columns = new HashSet<string>(columns.Where(x => !string.IsNullOrWhiteSpace(x)), StringComparer.OrdinalIgnoreCase);
        Indexes = new HashSet<string>(indexes.Where(x => !string.IsNullOrWhiteSpace(x)), StringComparer.OrdinalIgnoreCase);
    }

    public bool Exists { get; }
    public HashSet<string> Columns { get; }
    public HashSet<string> Indexes { get; }
}