import { EnumType, StringType, TextType } from '@mikro-orm/core';
import { SchemaHelper } from '../../schema/SchemaHelper.js';
export class MySqlSchemaHelper extends SchemaHelper {
  #cache = {};
  static DEFAULT_VALUES = {
    'now()': ['now()', 'current_timestamp'],
    'current_timestamp(?)': ['current_timestamp(?)'],
    0: ['0', 'false'],
  };
  getSchemaBeginning(charset, disableForeignKeys) {
    if (disableForeignKeys) {
      return `set names ${charset};\n${this.disableForeignKeysSQL()}\n\n`;
    }
    return `set names ${charset};\n\n`;
  }
  disableForeignKeysSQL() {
    return 'set foreign_key_checks = 0;';
  }
  enableForeignKeysSQL() {
    return 'set foreign_key_checks = 1;';
  }
  finalizeTable(table, charset, collate) {
    let sql = ` default character set ${charset}`;
    if (collate) {
      sql += ` collate ${collate}`;
    }
    sql += ' engine = InnoDB';
    if (table.comment) {
      sql += ` comment = ${this.platform.quoteValue(table.comment)}`;
    }
    return sql;
  }
  getListTablesSQL() {
    return `select table_name as table_name, nullif(table_schema, schema()) as schema_name, table_comment as table_comment from information_schema.tables where table_type = 'BASE TABLE' and table_schema = schema()`;
  }
  getListViewsSQL() {
    return `select table_name as view_name, nullif(table_schema, schema()) as schema_name, view_definition from information_schema.views where table_schema = schema()`;
  }
  async loadViews(schema, connection, schemaName) {
    const views = await connection.execute(this.getListViewsSQL());
    for (const view of views) {
      // MySQL information_schema.views.view_definition requires SHOW VIEW privilege
      // and may return NULL. Use SHOW CREATE VIEW as fallback.
      let definition = view.view_definition?.trim();
      if (!definition) {
        const createView = await connection.execute(`show create view \`${view.view_name}\``);
        if (createView[0]?.['Create View']) {
          // Extract SELECT statement from CREATE VIEW ... AS SELECT ...
          const match = /\bAS\s+(.+)$/is.exec(createView[0]['Create View']);
          definition = match?.[1]?.trim();
        }
      }
      if (definition) {
        schema.addView(view.view_name, view.schema_name ?? undefined, definition);
      }
    }
  }
  async loadInformationSchema(schema, connection, tables) {
    if (tables.length === 0) {
      return;
    }
    const columns = await this.getAllColumns(connection, tables);
    const indexes = await this.getAllIndexes(connection, tables);
    const checks = await this.getAllChecks(connection, tables);
    const fks = await this.getAllForeignKeys(connection, tables);
    const enums = await this.getAllEnumDefinitions(connection, tables);
    for (const t of tables) {
      const key = this.getTableKey(t);
      const table = schema.addTable(t.table_name, t.schema_name, t.table_comment);
      const pks = await this.getPrimaryKeys(connection, indexes[key], table.name, table.schema);
      table.init(columns[key], indexes[key], checks[key], pks, fks[key], enums[key]);
    }
  }
  async getAllIndexes(connection, tables) {
    const sql = `select table_name as table_name, nullif(table_schema, schema()) as schema_name, index_name as index_name, non_unique as non_unique, column_name as column_name, index_type as index_type, sub_part as sub_part, collation as sort_order /*!80013 , expression as expression, is_visible as is_visible */
        from information_schema.statistics where table_schema = database()
        and table_name in (${tables.map(t => this.platform.quoteValue(t.table_name)).join(', ')})
        order by schema_name, table_name, index_name, seq_in_index`;
    const allIndexes = await connection.execute(sql);
    const ret = {};
    for (const index of allIndexes) {
      const key = this.getTableKey(index);
      const indexDef = {
        columnNames: [index.column_name],
        keyName: index.index_name,
        unique: !index.non_unique,
        primary: index.index_name === 'PRIMARY',
        constraint: !index.non_unique,
      };
      // Capture column options (prefix length, sort order)
      if (index.sub_part != null || index.sort_order === 'D') {
        indexDef.columns = [
          {
            name: index.column_name,
            ...(index.sub_part != null && { length: index.sub_part }),
            ...(index.sort_order === 'D' && { sort: 'DESC' }),
          },
        ];
      }
      // Capture index type for fulltext and spatial indexes
      if (index.index_type === 'FULLTEXT') {
        indexDef.type = 'fulltext';
      } else if (index.index_type === 'SPATIAL') {
        /* v8 ignore next */
        indexDef.type = 'spatial';
      }
      // Capture invisible flag (MySQL 8.0.13+)
      if (index.is_visible === 'NO') {
        indexDef.invisible = true;
      }
      if (!index.column_name || index.expression?.match(/ where /i)) {
        indexDef.expression = index.expression; // required for the `getCreateIndexSQL()` call
        indexDef.expression = this.getCreateIndexSQL(index.table_name, indexDef, !!index.expression);
      }
      ret[key] ??= [];
      ret[key].push(indexDef);
    }
    for (const key of Object.keys(ret)) {
      ret[key] = await this.mapIndexes(ret[key]);
    }
    return ret;
  }
  getCreateIndexSQL(tableName, index, partialExpression = false) {
    /* v8 ignore next */
    if (index.expression && !partialExpression) {
      return index.expression;
    }
    tableName = this.quote(tableName);
    const keyName = this.quote(index.keyName);
    let sql = `alter table ${tableName} add ${index.unique ? 'unique' : 'index'} ${keyName} `;
    if (index.expression && partialExpression) {
      sql += `(${index.expression})`;
      return this.appendMySqlIndexSuffix(sql, index);
    }
    // JSON columns can have unique index but not unique constraint, and we need to distinguish those, so we can properly drop them
    if (index.columnNames.some(column => column.includes('.'))) {
      const columns = this.platform.getJsonIndexDefinition(index);
      sql = `alter table ${tableName} add ${index.unique ? 'unique ' : ''}index ${keyName} `;
      sql += `(${columns.join(', ')})`;
      return this.appendMySqlIndexSuffix(sql, index);
    }
    // Build column list with advanced options
    const columns = this.getIndexColumns(index);
    sql += `(${columns})`;
    return this.appendMySqlIndexSuffix(sql, index);
  }
  /**
   * Build the column list for a MySQL index, with MySQL-specific handling for collation.
   * MySQL requires collation to be specified as an expression: (column_name COLLATE collation_name)
   */
  getIndexColumns(index) {
    if (index.columns?.length) {
      return index.columns
        .map(col => {
          const quotedName = this.quote(col.name);
          // MySQL supports collation via expression: (column_name COLLATE collation_name)
          // When collation is specified, wrap in parentheses as an expression
          if (col.collation) {
            let expr = col.length ? `${quotedName}(${col.length})` : quotedName;
            expr = `(${expr} collate ${col.collation})`;
            // Sort order comes after the expression
            if (col.sort) {
              expr += ` ${col.sort}`;
            }
            return expr;
          }
          // Standard column definition without collation
          let colDef = quotedName;
          // MySQL supports prefix length
          if (col.length) {
            colDef += `(${col.length})`;
          }
          // MySQL supports sort order
          if (col.sort) {
            colDef += ` ${col.sort}`;
          }
          return colDef;
        })
        .join(', ');
    }
    return index.columnNames.map(c => this.quote(c)).join(', ');
  }
  /**
   * Append MySQL-specific index suffixes like INVISIBLE.
   */
  appendMySqlIndexSuffix(sql, index) {
    // MySQL 8.0+ supports INVISIBLE indexes
    if (index.invisible) {
      sql += ' invisible';
    }
    return sql;
  }
  async getAllColumns(connection, tables) {
    const sql = `select table_name as table_name,
      nullif(table_schema, schema()) as schema_name,
      column_name as column_name,
      column_default as column_default,
      nullif(column_comment, '') as column_comment,
      is_nullable as is_nullable,
      data_type as data_type,
      column_type as column_type,
      column_key as column_key,
      extra as extra,
      generation_expression as generation_expression,
      numeric_precision as numeric_precision,
      numeric_scale as numeric_scale,
      ifnull(datetime_precision, character_maximum_length) length
      from information_schema.columns where table_schema = database() and table_name in (${tables.map(t => this.platform.quoteValue(t.table_name))})
      order by ordinal_position`;
    const allColumns = await connection.execute(sql);
    const str = val => (val != null ? '' + val : val);
    const extra = val =>
      val.replace(/auto_increment|default_generated|(stored|virtual) generated/i, '').trim() || undefined;
    const ret = {};
    for (const col of allColumns) {
      const mappedType = this.platform.getMappedType(col.column_type);
      const defaultValue = str(
        this.normalizeDefaultValue(
          mappedType.compareAsType() === 'boolean' && ['0', '1'].includes(col.column_default)
            ? ['false', 'true'][+col.column_default]
            : col.column_default,
          col.length,
        ),
      );
      const key = this.getTableKey(col);
      const generated = col.generation_expression
        ? `(${col.generation_expression.replaceAll(`\\'`, `'`)}) ${col.extra.match(/stored generated/i) ? 'stored' : 'virtual'}`
        : undefined;
      ret[key] ??= [];
      ret[key].push({
        name: col.column_name,
        type: this.platform.isNumericColumn(mappedType)
          ? col.column_type.replace(/ unsigned$/, '').replace(/\(\d+\)$/, '')
          : col.column_type,
        mappedType,
        unsigned: col.column_type.endsWith(' unsigned'),
        length: col.length,
        default: this.wrap(defaultValue, mappedType),
        nullable: col.is_nullable === 'YES',
        primary: col.column_key === 'PRI',
        unique: col.column_key === 'UNI',
        autoincrement: col.extra === 'auto_increment',
        precision: col.numeric_precision,
        scale: col.numeric_scale,
        comment: col.column_comment,
        extra: extra(col.extra),
        generated,
      });
    }
    return ret;
  }
  async getAllChecks(connection, tables) {
    /* v8 ignore next */
    if (!(await this.supportsCheckConstraints(connection))) {
      return {};
    }
    const sql = this.getChecksSQL(tables);
    const allChecks = await connection.execute(sql);
    const ret = {};
    for (const check of allChecks) {
      const key = this.getTableKey(check);
      ret[key] ??= [];
      ret[key].push({
        name: check.name,
        columnName: check.column_name,
        definition: `check ${check.expression}`,
        expression: check.expression.replace(/^\((.*)\)$/, '$1'),
      });
    }
    return ret;
  }
  async getAllForeignKeys(connection, tables) {
    const sql = `select k.constraint_name as constraint_name, nullif(k.table_schema, schema()) as schema_name, k.table_name as table_name, k.column_name as column_name, k.referenced_table_name as referenced_table_name, k.referenced_column_name as referenced_column_name, c.update_rule as update_rule, c.delete_rule as delete_rule
        from information_schema.key_column_usage k
        inner join information_schema.referential_constraints c on c.constraint_name = k.constraint_name and c.table_name = k.table_name
        where k.table_name in (${tables.map(t => this.platform.quoteValue(t.table_name)).join(', ')})
        and k.table_schema = database() and c.constraint_schema = database() and k.referenced_column_name is not null
        order by constraint_name, k.ordinal_position`;
    const allFks = await connection.execute(sql);
    const ret = {};
    for (const fk of allFks) {
      const key = this.getTableKey(fk);
      ret[key] ??= [];
      ret[key].push(fk);
    }
    Object.keys(ret).forEach(key => {
      const parts = key.split('.');
      /* v8 ignore next */
      const schemaName = parts.length > 1 ? parts[0] : undefined;
      ret[key] = this.mapForeignKeys(ret[key], key, schemaName);
    });
    return ret;
  }
  getPreAlterTable(tableDiff, safe) {
    // Dropping primary keys requires to unset autoincrement attribute on the particular column first.
    const pk = Object.values(tableDiff.removedIndexes).find(idx => idx.primary);
    if (!pk || safe) {
      return [];
    }
    return pk.columnNames
      .filter(col => tableDiff.fromTable.hasColumn(col))
      .map(col => tableDiff.fromTable.getColumn(col))
      .filter(col => col.autoincrement)
      .map(
        col =>
          `alter table \`${tableDiff.name}\` modify \`${col.name}\` ${this.getColumnDeclarationSQL({ ...col, autoincrement: false })}`,
      );
  }
  getRenameColumnSQL(tableName, oldColumnName, to) {
    tableName = this.quote(tableName);
    oldColumnName = this.quote(oldColumnName);
    const columnName = this.quote(to.name);
    return `alter table ${tableName} change ${oldColumnName} ${columnName} ${this.getColumnDeclarationSQL(to)}`;
  }
  getRenameIndexSQL(tableName, index, oldIndexName) {
    tableName = this.quote(tableName);
    oldIndexName = this.quote(oldIndexName);
    const keyName = this.quote(index.keyName);
    return [`alter table ${tableName} rename index ${oldIndexName} to ${keyName}`];
  }
  getChangeColumnCommentSQL(tableName, to, schemaName) {
    tableName = this.quote(tableName);
    const columnName = this.quote(to.name);
    return `alter table ${tableName} modify ${columnName} ${this.getColumnDeclarationSQL(to)}`;
  }
  alterTableColumn(column, table, changedProperties) {
    const col = this.createTableColumn(column, table, changedProperties);
    return [`alter table ${table.getQuotedName()} modify ${col}`];
  }
  getColumnDeclarationSQL(col) {
    let ret = col.type;
    ret += col.unsigned ? ' unsigned' : '';
    ret += col.autoincrement ? ' auto_increment' : '';
    ret += ' ';
    ret += col.nullable ? 'null' : 'not null';
    ret += col.default ? ' default ' + col.default : '';
    ret += col.comment ? ` comment ${this.platform.quoteValue(col.comment)}` : '';
    return ret;
  }
  async getAllEnumDefinitions(connection, tables) {
    const sql = `select column_name as column_name, column_type as column_type, table_name as table_name
      from information_schema.columns
      where data_type = 'enum' and table_name in (${tables.map(t => `'${t.table_name}'`).join(', ')}) and table_schema = database()`;
    const enums = await connection.execute(sql);
    return enums.reduce((o, item) => {
      o[item.table_name] ??= {};
      o[item.table_name][item.column_name] = item.column_type
        .match(/enum\((.*)\)/)[1]
        .split(',')
        .map(item => /'(.*)'/.exec(item)[1]);
      return o;
    }, {});
  }
  async supportsCheckConstraints(connection) {
    if (this.#cache.supportsCheckConstraints != null) {
      return this.#cache.supportsCheckConstraints;
    }
    const sql = `select 1 from information_schema.tables where table_name = 'CHECK_CONSTRAINTS' and table_schema = 'information_schema'`;
    const res = await connection.execute(sql);
    return (this.#cache.supportsCheckConstraints = res.length > 0);
  }
  getChecksSQL(tables) {
    return `select cc.constraint_schema as table_schema, tc.table_name as table_name, cc.constraint_name as name, cc.check_clause as expression
      from information_schema.check_constraints cc
      join information_schema.table_constraints tc
        on tc.constraint_schema = cc.constraint_schema
        and tc.constraint_name = cc.constraint_name
        and constraint_type = 'CHECK'
      where tc.table_name in (${tables.map(t => this.platform.quoteValue(t.table_name))}) and tc.constraint_schema = database()
      order by tc.constraint_name`;
  }
  normalizeDefaultValue(defaultValue, length) {
    return super.normalizeDefaultValue(defaultValue, length, MySqlSchemaHelper.DEFAULT_VALUES);
  }
  wrap(val, type) {
    const stringType = type instanceof StringType || type instanceof TextType || type instanceof EnumType;
    return typeof val === 'string' && val.length > 0 && stringType ? this.platform.quoteValue(val) : val;
  }
}