import type { UserConfig } from '@hey-api/openapi-ts'
import fs from 'node:fs'
import path from 'node:path'
import { fileURLToPath } from 'node:url'
import { $, defineConfig } from '@hey-api/openapi-ts'

type JsonObject = Record<string, unknown>

type SwaggerSchema = JsonObject & {
  $ref?: string
}

type OpenApiMediaType = JsonObject & {
  schema?: SwaggerSchema
}

type OpenApiResponse = JsonObject & {
  content?: Record<string, OpenApiMediaType>
}

type OpenApiComponents = JsonObject & {
  schemas?: Record<string, SwaggerSchema>
}

type SwaggerOperation = JsonObject & {
  operationId?: string
  responses?: Record<string, OpenApiResponse>
}

type SwaggerDocument = JsonObject & {
  components?: OpenApiComponents
  openapi?: string
  paths?: Record<string, Record<string, unknown>>
}

type ApiSpec = {
  filename: string
  name: string
}

type ApiJob = {
  clean?: boolean
  document: SwaggerDocument
  outputPath: string
  plugins?: UserConfig['plugins']
  source?: {
    callback: () => void
    enabled: true
    path: null
    serialize: () => string
  }
}

type ApiContractOperation = {
  method: string
  path: string
}

const currentDir = path.dirname(fileURLToPath(import.meta.url))
const apiOpenApiDir = path.resolve(currentDir, 'openapi')

const operationMethods = new Set(['delete', 'get', 'patch', 'post', 'put'])
const pydanticDecimalStringPattern = '^(?!^[-+.]*$)[+-]?0*\\d*\\.?\\d*$'
const codegenSafeDecimalStringPattern = '^(?![-+.]*$)[+-]?0*\\d*\\.?\\d*$'
const fastOpenApiConsoleSpecFilename = 'fastopenapi-console-openapi.json'
const fastOpenApiConsolePathPrefix = '/console/api'

const apiSpecs: ApiSpec[] = [
  { filename: 'console-openapi.json', name: 'console' },
  { filename: 'web-openapi.json', name: 'web' },
  { filename: 'service-openapi.json', name: 'service' },
  { filename: 'openapi-openapi.json', name: 'openapi' },
]

const isObject = (value: unknown): value is JsonObject => {
  return !!value && typeof value === 'object' && !Array.isArray(value)
}

const toWords = (value: string) => {
  return value
    .replace(/[{}]/g, '')
    .replace(/([a-z0-9])([A-Z])/g, '$1 $2')
    .split(/[^a-z0-9]+/i)
    .filter(Boolean)
}

const toPascalCase = (words: string[]) => {
  return words.map((word) => `${word.charAt(0).toUpperCase()}${word.slice(1)}`).join('')
}

const toCamelCase = (words: string[]) => {
  const pascal = toPascalCase(words)
  return `${pascal.charAt(0).toLowerCase()}${pascal.slice(1)}`
}

const toKebabCase = (value: string) => {
  return toWords(value).join('-').toLowerCase()
}

const segmentWords = (segment: string) => {
  if (segment.startsWith('{') && segment.endsWith('}')) return ['by', ...toWords(segment)]

  return toWords(segment)
}

// Split on `:` too so custom methods nest as their own node (apps.byAppId.run), not apps.appIdRun.
const routeNamingSegments = (routePath: string) => routePath.split(/[/:]/).filter(Boolean)

const routeWords = (routePath: string) => {
  return routeNamingSegments(routePath).flatMap(segmentWords)
}

const operationId = (method: string, routePath: string) => {
  return toCamelCase([
    method,
    ...(routeWords(routePath).length > 0 ? routeWords(routePath) : ['root']),
  ])
}

const contractPathSegments = (operation: ApiContractOperation) => {
  const segments = routeNamingSegments(operation.path).map((segment) =>
    toCamelCase(segmentWords(segment)),
  )

  return [...(segments.length > 0 ? segments : ['root']), operation.method.toLowerCase()]
}

const readApiSwagger = (filename: string): SwaggerDocument => {
  const specPath = path.join(apiOpenApiDir, filename)

  if (!fs.existsSync(specPath)) {
    throw new Error(
      `Missing API OpenAPI spec: ${specPath}. Run "pnpm gen-api-openapi" from packages/contracts/ first.`,
    )
  }

  const rawSpec = JSON.parse(fs.readFileSync(specPath, 'utf8'))
  if (!isObject(rawSpec) || !isObject(rawSpec.paths))
    throw new Error(`Invalid API OpenAPI spec: ${specPath}`)

  return rawSpec as SwaggerDocument
}

const clone = <T>(value: T): T => {
  return JSON.parse(JSON.stringify(value)) as T
}

const componentSchemaRefPrefix = '#/components/schemas/'

const schemaNameFromRef = (ref: string) => {
  if (ref.startsWith(componentSchemaRefPrefix)) return ref.slice(componentSchemaRefPrefix.length)
  return undefined
}

const getDocumentSchemas = (document: SwaggerDocument) => {
  const components = (document.components ??= {})
  return (components.schemas ??= {})
}

const collectSchemaRefs = (value: unknown, refs: Set<string>, visited = new WeakSet<object>()) => {
  if (!value || typeof value !== 'object') return

  if (visited.has(value)) return

  visited.add(value)

  if (Array.isArray(value)) {
    value.forEach((item) => collectSchemaRefs(item, refs, visited))
    return
  }

  const objectValue = value as JsonObject
  const ref = objectValue.$ref
  if (typeof ref === 'string') {
    const refName = schemaNameFromRef(ref)
    if (refName) refs.add(refName)
  }

  Object.values(objectValue).forEach((item) => collectSchemaRefs(item, refs, visited))
}

const addOperationIds = (document: SwaggerDocument) => {
  for (const [routePath, pathItem] of Object.entries(document.paths ?? {})) {
    for (const [method, operation] of Object.entries(pathItem)) {
      if (!operationMethods.has(method) || !isObject(operation)) continue

      const swaggerOperation = operation as SwaggerOperation
      swaggerOperation.operationId = operationId(method, routePath)
    }
  }
}

const normalizeOpaqueContractResponses = (document: SwaggerDocument) => {
  // This runs before contract filtering. Flask-RESTX often emits plain success responses
  // without a body schema; give those routes an opaque output so they stay in oRPC.
  for (const pathItem of Object.values(document.paths ?? {})) {
    for (const [method, operation] of Object.entries(pathItem)) {
      if (!operationMethods.has(method) || !isObject(operation)) continue

      const swaggerOperation = operation as SwaggerOperation
      for (const [status, response] of Object.entries(swaggerOperation.responses ?? {})) {
        // Ignore non-2xx or 204 or those w/o a response field
        if (!/^2\d\d$/.test(status) || status === '204' || !isObject(response)) continue

        const content = response.content
        if (!isObject(content) || Object.keys(content).length === 0) {
          // No response specification, fill a dummy opaque resp
          response.content = {
            'application/json': {
              schema: {
                additionalProperties: true,
                type: 'object',
              },
            },
          }
          continue
        }

        for (const [mediaType, media] of Object.entries(content)) {
          if (mediaType !== 'application/json' && mediaType !== 'text/event-stream') continue
          if (!isObject(media) || isObject(media.schema)) continue

          // JSON/SSE media without a schema traps heyapi. Patch only that media entry so
          // sibling binary media keeps heyapi's Blob | File inference.
          // Still a dummy opaque resp
          media.schema = {
            additionalProperties: true,
            type: 'object',
          }
        }
      }
    }
  }
}

const hasSuccessResponse = (operation: SwaggerOperation) => {
  return Object.entries(operation.responses ?? {}).some(([status, response]) => {
    if (!/^2\d\d$/.test(status)) return false
    if (!isObject(response)) return false
    const content = (response as JsonObject).content
    // 204 No Content is a valid success response without a body
    if (!isObject(content) || Object.keys(content).length === 0) return status === '204'
    return true
  })
}

const filterContractOperations = (document: SwaggerDocument) => {
  for (const [routePath, pathItem] of Object.entries(document.paths ?? {})) {
    for (const [method, operation] of Object.entries(pathItem)) {
      if (!operationMethods.has(method) || !isObject(operation)) continue

      if (!hasSuccessResponse(operation as SwaggerOperation)) delete pathItem[method]
    }

    const hasOperations = Object.entries(pathItem).some(
      ([method, operation]) => operationMethods.has(method) && isObject(operation),
    )

    if (!hasOperations) delete document.paths?.[routePath]
  }
}

const normalizeApiSwagger = (document: SwaggerDocument) => {
  normalizeOpaqueContractResponses(document)
  filterContractOperations(document)
  addOperationIds(document)

  return document
}

const mergeFastOpenApiConsoleSwagger = (document: SwaggerDocument) => {
  const fastOpenApiDocument = readApiSwagger(fastOpenApiConsoleSpecFilename)
  const targetPaths = (document.paths ??= {})

  for (const [routePath, pathItem] of Object.entries(fastOpenApiDocument.paths ?? {})) {
    const contractPath = routePath.startsWith(fastOpenApiConsolePathPrefix)
      ? routePath.slice(fastOpenApiConsolePathPrefix.length) || '/'
      : routePath

    if (targetPaths[contractPath])
      throw new Error(`Duplicate console API path after FastOpenAPI merge: ${contractPath}`)

    targetPaths[contractPath] = pathItem
  }

  const targetSchemas = getDocumentSchemas(document)
  const sourceSchemas = getDocumentSchemas(fastOpenApiDocument)
  for (const [schemaName, schema] of Object.entries(sourceSchemas)) {
    if (targetSchemas[schemaName])
      throw new Error(`Duplicate console API schema after FastOpenAPI merge: ${schemaName}`)

    targetSchemas[schemaName] = schema
  }

  return document
}

const topLevelPathSegment = (routePath: string) => {
  return routePath.split('/').filter(Boolean)[0] ?? 'root'
}

const selectReferencedSchemas = (
  schemas: Record<string, SwaggerSchema>,
  paths: Record<string, Record<string, unknown>>,
) => {
  const selectedSchemas: Record<string, SwaggerSchema> = {}
  const pendingRefs = new Set<string>()
  collectSchemaRefs(paths, pendingRefs)

  while (pendingRefs.size > 0) {
    const refName = pendingRefs.values().next().value
    if (!refName) break

    pendingRefs.delete(refName)

    if (selectedSchemas[refName]) continue

    const schema = schemas[refName]
    if (!schema) throw new Error(`Missing referenced schema: ${refName}`)

    selectedSchemas[refName] = schema

    const nestedRefs = new Set<string>()
    collectSchemaRefs(selectedSchemas[refName], nestedRefs)
    for (const nestedRef of nestedRefs) {
      if (!selectedSchemas[nestedRef]) pendingRefs.add(nestedRef)
    }
  }

  return selectedSchemas
}

const cloneDocumentWithPaths = (
  document: SwaggerDocument,
  paths: Record<string, Record<string, unknown>>,
) => {
  const { components: _components, paths: _paths, ...metadata } = document
  const clonedPaths = clone(paths)
  const components = clone(document.components ?? {})
  const sourceSchemas = getDocumentSchemas(document)

  components.schemas = selectReferencedSchemas(sourceSchemas, clonedPaths)

  return {
    ...clone(metadata),
    components,
    paths: clonedPaths,
  } satisfies SwaggerDocument
}

const consoleContractEntryContent = (segments: string[]) => {
  const contracts = segments.map((segment) => {
    return {
      importPath: toKebabCase(segment),
      name: toCamelCase(segmentWords(segment)),
    }
  })

  const contractEntries = contracts
    .map(
      (contract) =>
        `  ${contract.name}: () => import('./${contract.importPath}/orpc.gen').then(({ ${contract.name} }) => ({ ${contract.name} })),`,
    )
    .join('\n')

  return `// This file is auto-generated by @hey-api/openapi-ts

export const contractLoaders = {
${contractEntries}
}
`
}

const writeConsoleContractEntry = (segments: string[]) => {
  const entryPath = path.resolve(currentDir, 'generated/api/console/orpc.gen.ts')
  fs.mkdirSync(path.dirname(entryPath), { recursive: true })
  fs.writeFileSync(entryPath, consoleContractEntryContent(segments))
}

const consoleRouterContractContent = (segments: string[]) => {
  const contracts = segments.map((segment) => {
    return {
      importPath: toKebabCase(segment),
      name: toCamelCase(segmentWords(segment)),
    }
  })

  const imports = contracts
    .map((contract) => `import { ${contract.name} } from './${contract.importPath}/orpc.gen'`)
    .join('\n')

  const communityContractEntries = contracts.map((contract) => `  ${contract.name},`).join('\n')

  return `// This file is auto-generated by packages/contracts/openapi-ts.api.config.ts

${imports}
import { contract as enterpriseContract } from '../../enterprise/orpc.gen'

const communityContract = {
${communityContractEntries}
}

export const consoleRouterContract = {
  enterprise: enterpriseContract,
  ...communityContract,
}
`
}

const writeConsoleRouterContract = (segments: string[]) => {
  const routerPath = path.resolve(currentDir, 'generated/api/console/router.gen.ts')
  fs.mkdirSync(path.dirname(routerPath), { recursive: true })
  fs.writeFileSync(routerPath, consoleRouterContractContent(segments))
}

const createConsoleContractEntryJob = (document: SwaggerDocument, segments: string[]): ApiJob => {
  return {
    clean: false,
    document,
    outputPath: 'generated/api/console',
    plugins: [],
    source: {
      callback: () => {
        writeConsoleContractEntry(segments)
        writeConsoleRouterContract(segments)
      },
      enabled: true,
      path: null,
      serialize: () => '',
    },
  }
}

const splitConsoleDocument = (document: SwaggerDocument) => {
  const pathsBySegment = new Map<string, Record<string, Record<string, unknown>>>()

  for (const [routePath, pathItem] of Object.entries(document.paths ?? {})) {
    const segment = topLevelPathSegment(routePath)
    const paths = pathsBySegment.get(segment) ?? {}
    paths[routePath] = pathItem
    pathsBySegment.set(segment, paths)
  }

  const segments = [...pathsBySegment.keys()].sort((left, right) => left.localeCompare(right))
  const jobs = segments.map(
    (segment): ApiJob => ({
      document: cloneDocumentWithPaths(document, pathsBySegment.get(segment) ?? {}),
      outputPath: `generated/api/console/${toKebabCase(segment)}`,
    }),
  )

  return [...jobs, createConsoleContractEntryJob(document, segments)]
}

const createApiJobs = (spec: ApiSpec): ApiJob[] => {
  const document = normalizeApiSwagger(
    spec.name === 'console'
      ? mergeFastOpenApiConsoleSwagger(readApiSwagger(spec.filename))
      : readApiSwagger(spec.filename),
  )

  if (spec.name === 'console') return splitConsoleDocument(document)

  return [
    {
      document,
      outputPath: `generated/api/${spec.name}`,
    },
  ]
}

const apiJobs = apiSpecs.flatMap(createApiJobs)

const createApiConfig = (job: ApiJob): UserConfig => ({
  input: job.document,
  logs: {
    file: false,
  },
  output: {
    ...(job.clean === undefined ? {} : { clean: job.clean }),
    entryFile: false,
    fileName: {
      suffix: '.gen',
    },
    path: job.outputPath,
    ...(job.source ? { source: job.source } : {}),
  },
  plugins: job.plugins ?? [
    {
      comments: false,
      name: '@hey-api/typescript',
    },
    {
      name: 'zod',
      '~resolvers': {
        string: (ctx) => {
          if (ctx.schema.format === 'binary')
            return $(ctx.symbols.z)
              .attr('custom')
              .call()
              .generic($.type.or($.type('Blob'), $.type('File')))

          if (ctx.schema.pattern === pydanticDecimalStringPattern) {
            // the pydantic generated regex will emit error like
            // regexp/no-useless-assertions, so patch the regex here
            return $(ctx.symbols.z)
              .attr('string')
              .call()
              .attr('regex')
              .call($.regexp(codegenSafeDecimalStringPattern))
          }

          return undefined
        },
      },
    },
    {
      contracts: {
        contractName: {
          casing: 'camelCase',
          name: '{{name}}',
        },
        nesting: contractPathSegments,
        segmentName: {
          casing: 'camelCase',
          name: '{{name}}',
        },
        strategy: 'single',
      },
      name: 'orpc',
      validator: 'zod',
    },
  ],
})

export default defineConfig(apiJobs.map(createApiConfig))