/**
 * Channels Code Generator
 *
 * Generates TypeScript types and React hooks from Channels OpenAPI schema.
 * Uses openapi-typescript for robust type generation.
 */

import openapiTS, { astToString } from 'openapi-typescript'

/**
 * Generate channels TypeScript types using openapi-typescript.
 */
export async function generateChannelsTypes(schema) {
  // Generate types using openapi-typescript
  const ast = await openapiTS(schema)
  const typesCode = astToString(ast)

  const lines = [
    '// AUTO-GENERATED by mizan - do not edit manually',
    '// Regenerate with: npm run schemas',
    '',
    '// ============================================================================',
    '// OpenAPI Types (generated by openapi-typescript)',
    '// ============================================================================',
    '',
    typesCode,
    '',
  ]

  // Extract channel metadata from x-mizan-channels extension
  const channels = schema['x-mizan-channels'] || []

  if (channels.length > 0) {
    lines.push('// ============================================================================')
    lines.push('// Convenience Type Exports')
    lines.push('// ============================================================================')
    lines.push('')

    for (const channel of channels) {
      if (channel.hasParams) {
        lines.push(`export type ${channel.paramsType} = components["schemas"]["${channel.paramsType}"]`)
      }
      if (channel.hasReactMessage) {
        lines.push(`export type ${channel.reactMessageType} = components["schemas"]["${channel.reactMessageType}"]`)
      }
      if (channel.hasDjangoMessage) {
        lines.push(`export type ${channel.djangoMessageType} = components["schemas"]["${channel.djangoMessageType}"]`)
      }
    }

    lines.push('')
    lines.push('// ============================================================================')
    lines.push('// Channel Registry')
    lines.push('// ============================================================================')
    lines.push('')
    lines.push('export const CHANNELS = {')
    for (const channel of channels) {
      lines.push(`  ${channel.name}: {`)
      lines.push(`    name: '${channel.name}',`)
      lines.push(`    pascalName: '${channel.pascalName}',`)
      lines.push(`    hasParams: ${channel.hasParams},`)
      lines.push(`    hasReactMessage: ${channel.hasReactMessage},`)
      lines.push(`    hasDjangoMessage: ${channel.hasDjangoMessage},`)
      if (channel.hasParams) {
        lines.push(`    paramsType: '${channel.paramsType}',`)
      }
      if (channel.hasReactMessage) {
        lines.push(`    reactMessageType: '${channel.reactMessageType}',`)
      }
      if (channel.hasDjangoMessage) {
        lines.push(`    djangoMessageType: '${channel.djangoMessageType}',`)
      }
      lines.push(`  },`)
    }
    lines.push('} as const')
  } else {
    lines.push('export const CHANNELS = {} as const')
  }

  lines.push('')

  return lines.join('\n')
}

/**
 * Generate channel hooks from metadata.
 */
export function generateChannelsHooks(schema) {
  const channels = schema['x-mizan-channels'] || []

  if (channels.length === 0) {
    return null
  }

  const lines = [
    "'use client'",
    '',
    '// AUTO-GENERATED by mizan - do not edit manually',
    '// Regenerate with: npm run schemas',
    '',
    "import { useChannel, type ChannelSubscription } from 'mizan/channels'",
    '',
  ]

  // Collect type imports
  const typeImports = []
  for (const channel of channels) {
    if (channel.hasParams) typeImports.push(channel.paramsType)
    if (channel.hasReactMessage) typeImports.push(channel.reactMessageType)
    if (channel.hasDjangoMessage) typeImports.push(channel.djangoMessageType)
  }

  if (typeImports.length > 0) {
    lines.push(`import type { ${typeImports.join(', ')} } from './generated.channels'`)
    lines.push('')
  }

  // Generate hooks for each channel
  lines.push('// ============================================================================')
  lines.push('// Channel Hooks')
  lines.push('// ============================================================================')
  lines.push('')

  for (const channel of channels) {
    const paramsType = channel.hasParams ? channel.paramsType : 'Record<string, never>'
    const reactMsgType = channel.hasReactMessage ? channel.reactMessageType : 'never'
    const djangoMsgType = channel.hasDjangoMessage ? channel.djangoMessageType : 'never'

    lines.push(`/**`)
    lines.push(` * Hook for the ${channel.name} channel.`)
    lines.push(` */`)

    if (channel.hasParams) {
      lines.push(`export function use${channel.pascalName}Channel(params: ${paramsType}): ChannelSubscription<${paramsType}, ${djangoMsgType}, ${reactMsgType}> {`)
      lines.push(`  return useChannel('${channel.name}', params)`)
    } else {
      lines.push(`export function use${channel.pascalName}Channel(): ChannelSubscription<Record<string, never>, ${djangoMsgType}, ${reactMsgType}> {`)
      lines.push(`  return useChannel('${channel.name}', {})`)
    }
    lines.push('}')
    lines.push('')
  }

  return lines.join('\n')
}

/**
 * Generate all channels files.
 */
export async function generateChannelsFiles(schema) {
  const types = await generateChannelsTypes(schema)
  const hooks = generateChannelsHooks(schema)

  return { types, hooks }
}