import {
  replaceSecretReference,
  generateDateFormatterCode,
  generateSafeJSONParseCode,
  generateSearchEscapeHelpersCode,
} from '../utils'

interface MySQLConfig {
  host?: string
  port?: number
  user?: string
  username?: string
  password?: string
  database?: string
  ssl?: boolean | { ca?: string; cert?: string; key?: string; rejectUnauthorized?: boolean }
  sslConfig?: { ca?: string; cert?: string; key?: string; rejectUnauthorized?: boolean }
}

export const generateMySQLFetcher = (
  config: Record<string, unknown>,
  tableName: string
): string => {
  const mysqlConfig = config as MySQLConfig
  const resolvedUser = mysqlConfig.user || mysqlConfig.username || null
  const hasCustomSSLConfig = !!mysqlConfig.sslConfig
  const defaultSSLEnabled = mysqlConfig.ssl !== false
  const database = mysqlConfig.database

  const sslConfigString = hasCustomSSLConfig
    ? `{
      ${mysqlConfig.sslConfig.ca ? `ca: ${replaceSecretReference(mysqlConfig.sslConfig.ca)},` : ''}
      ${
        mysqlConfig.sslConfig.cert
          ? `cert: ${replaceSecretReference(mysqlConfig.sslConfig.cert)},`
          : ''
      }
      ${
        mysqlConfig.sslConfig.key
          ? `key: ${replaceSecretReference(mysqlConfig.sslConfig.key)},`
          : ''
      }
      rejectUnauthorized: ${
        mysqlConfig.sslConfig.rejectUnauthorized !== undefined
          ? mysqlConfig.sslConfig.rejectUnauthorized
          : true
      }
    }`
    : defaultSSLEnabled
    ? `{ rejectUnauthorized: true }`
    : 'false'

  return `import mysql from 'mysql2/promise'

const getConnection = () => {
  return mysql.createConnection({
    host: ${JSON.stringify(mysqlConfig.host)},
    port: ${mysqlConfig.port || 3306},
    user: ${resolvedUser !== null ? JSON.stringify(resolvedUser) : 'undefined'},
    password: ${replaceSecretReference(mysqlConfig.password)},
    database: ${JSON.stringify(mysqlConfig.database)},
    ssl: ${sslConfigString}
  })
}

${generateSafeJSONParseCode()}

${generateSearchEscapeHelpersCode()}

// Helper function to process filters and build conditions
const processFilters = (filters, conditions, queryParams) => {
  if (!filters) return
  
  const parsedFilters = safeJSONParse(filters)
  
  if (Array.isArray(parsedFilters)) {
    parsedFilters.forEach((filter) => {
      if (!filter.source || filter.destination === undefined) return
      
      const field = mysql.escapeId(filter.source)
      const value = filter.destination
      const operand = filter.operand || '='
      
      if (Array.isArray(value)) {
        if (value.length === 0) return
        const placeholders = value.map(() => '?').join(', ')
        queryParams.push(...value)
        if (operand === '!=') {
          conditions.push(\`\${field} NOT IN (\${placeholders})\`)
        } else {
          conditions.push(\`\${field} IN (\${placeholders})\`)
        }
      } else {
        if (value === null) {
          if (operand === '=') {
            conditions.push(\`\${field} IS NULL\`)
          } else if (operand === '!=') {
            conditions.push(\`\${field} IS NOT NULL\`)
          }
        } else {
          // Validate operator to prevent SQL injection
          const validOps = ['=', '!=', '>', '<', '>=', '<=']
          const sqlOperator = validOps.includes(operand) ? operand : '='
          conditions.push(\`\${field} \${sqlOperator} ?\`)
          queryParams.push(value)
        }
      }
    })
  } else {
    Object.entries(parsedFilters).forEach(([key, value]) => {
      if (Array.isArray(value)) {
        const placeholders = value.map(() => '?').join(', ')
        queryParams.push(...value)
        conditions.push(\`\${mysql.escapeId(key)} IN (\${placeholders})\`)
      } else {
        conditions.push(\`\${mysql.escapeId(key)} = ?\`)
        queryParams.push(value)
      }
    })
  }
}

${generateDateFormatterCode()}

export default async function handler(req, res) {
  const connection = await getConnection()
  
  try {
    const { query, queryColumns, limit, page, perPage, sortBy, sortOrder, filters, sorts, offset } = req.query
    
    const conditions = []
    const queryParams = []
    
    if (query) {
      let columns = []
      
      if (queryColumns) {
        // Use specified columns. Wrap non-arrays so a single column
        // passed as a bare string doesn't get iterated as chars.
        const parsed = safeJSONParse(queryColumns)
        columns = Array.isArray(parsed) ? parsed : (parsed ? [parsed] : [])
      } else {
        // Fallback: Get all columns from information_schema
        try {
          const [schemaRows] = await connection.query(
            \`SELECT COLUMN_NAME FROM information_schema.COLUMNS 
             WHERE TABLE_SCHEMA = ? AND TABLE_NAME = ? 
             ORDER BY ORDINAL_POSITION\`,
            [${JSON.stringify(database)}, ${JSON.stringify(tableName)}]
          )
          columns = schemaRows.map(row => row.COLUMN_NAME)
        } catch (schemaError) {
          console.warn('Failed to fetch column names from information_schema:', schemaError.message)
          // Continue without search if we can't get columns
        }
      }
      
      if (columns.length > 0) {
        const pattern = "%" + escapeLikePattern(query) + "%"
        const searchConditions = columns.map(
          (col) =>
            "LOWER(CAST(" + mysql.escapeId(sanitizeSearchIdentifier(col)) + " AS CHAR)) LIKE LOWER(?) ESCAPE '|'"
        )
        columns.forEach(() => queryParams.push(pattern))
        conditions.push("(" + searchConditions.join(" OR ") + ")")
      }
    }

    // Apply filters using helper function
    processFilters(filters, conditions, queryParams)
    
    let sql = \`SELECT * FROM \${mysql.escapeId('${tableName}')}\`
    
    if (conditions.length > 0) {
      sql += \` WHERE \${conditions.join(' AND ')}\`
    }
    
    // Handle sorts - new array format
    if (sorts) {
      const parsedSorts = safeJSONParse(sorts)
      if (Array.isArray(parsedSorts) && parsedSorts.length > 0) {
        const orderClauses = parsedSorts.map((sort) => {
          if (!sort.field) return null
          const order = (sort.order || '').toUpperCase().startsWith('DESC') ? 'DESC' : 'ASC'
          return \`\${mysql.escapeId(sort.field)} \${order}\`
        }).filter(Boolean)

        if (orderClauses.length > 0) {
          sql += \` ORDER BY \${orderClauses.join(', ')}\`
        }
      }
    } else if (sortBy) {
      sql += \` ORDER BY \${mysql.escapeId(sortBy)} \${(sortOrder || '').toUpperCase().startsWith('DESC') ? 'DESC' : 'ASC'}\`
    }
    
    const limitValue = limit || perPage
    const offsetValue = offset !== undefined ? parseInt(offset) : (page && perPage ? (parseInt(page) - 1) * parseInt(perPage) : undefined)
    
    if (limitValue) {
      sql += \` LIMIT \${limitValue}\`
    }
    
    if (offsetValue !== undefined) {
      sql += \` OFFSET \${offsetValue}\`
    }
    
    const [rows] = await connection.query(sql, queryParams)
    const rowArray = Array.isArray(rows) ? rows : []
    const plainRows = rowArray.map((row) =>
      row && typeof row.toJSON === 'function' ? row.toJSON() : row
    )
    const safeData = JSON.parse(JSON.stringify(plainRows, dateReplacer))

    return res.status(200).json({
      success: true,
      data: safeData,
      timestamp: Date.now()
    })
  } catch (error) {
    console.error('MySQL fetch error:', error)
    return res.status(500).json({
      success: false,
      error: error.message || 'Failed to fetch data',
      timestamp: Date.now()
    })
  } finally {
    if (connection) {
      try {
        await connection.end()
      } catch (error) {
        console.error('Error closing MySQL connection:', error)
      }
    }
  }
}
`
}

export const generateMySQLCountFetcher = (
  config: Record<string, unknown>,
  tableName: string
): string => {
  const mysqlConfig = config as MySQLConfig

  return `
async function getCount(req, res) {
  const connection = await getConnection()

  try {
    const { query, queryColumns, filters } = req.query
    const conditions = []
    const queryParams = []

    if (query) {
      let columns = []
      
      if (queryColumns) {
        // Use specified columns
        const parsed = safeJSONParse(queryColumns)
        columns = Array.isArray(parsed) ? parsed : [parsed]
      } else {
        // Fallback: Get all columns from information_schema
        try {
          const [schemaRows] = await connection.execute(
            \`SELECT COLUMN_NAME FROM information_schema.COLUMNS 
             WHERE TABLE_SCHEMA = ? AND TABLE_NAME = ? 
             ORDER BY ORDINAL_POSITION\`,
            [${JSON.stringify(mysqlConfig.database)}, ${JSON.stringify(tableName)}]
          )
          columns = schemaRows.map(row => row.COLUMN_NAME)
        } catch (schemaError) {
          console.warn('Failed to fetch column names from information_schema:', schemaError.message)
          // Continue without search if we can't get columns
        }
      }
      
      if (columns.length > 0) {
        const pattern = "%" + escapeLikePattern(query) + "%"
        const searchConditions = columns
          .map(
            (col) =>
              "LOWER(CAST(" + mysql.escapeId(sanitizeSearchIdentifier(col)) + " AS CHAR)) LIKE LOWER(?) ESCAPE '|'"
          )
          .join(" OR ")
        conditions.push("(" + searchConditions + ")")
        columns.forEach(() => queryParams.push(pattern))
      }
    }

    // Apply filters using helper function
    processFilters(filters, conditions, queryParams)

    let countSql = \`SELECT COUNT(*) as count FROM ${tableName}\`
    if (conditions.length > 0) {
      countSql += \` WHERE \${conditions.join(' AND ')}\`
    }

    const [rows] = await connection.query(countSql, queryParams)
    const count = rows[0].count

    return res.status(200).json({
      success: true,
      count: count,
      timestamp: Date.now()
    })
  } catch (error) {
    console.error('Error getting count:', error)
    return res.status(500).json({
      success: false,
      error: error.message || 'Failed to get count',
      timestamp: Date.now()
    })
  } finally {
    if (connection) {
      try {
        await connection.end()
      } catch (error) {
        console.error('Error closing MySQL connection:', error)
      }
    }
  }
}
`
}