/**
 * Request Builder — Schema-aware request construction with path/body/query/header discrimination
 */
import type { ResourceHierarchy, ModelState } from './stateful.js'
import { SeededRng } from '../infrastructure/seeded-rng.js'
import { CONTENT_TYPE } from '../infrastructure/http-executor.js'
import type { RouteContract } from '../types.js'

export interface RequestStructure {
  method: string
  url: string
  headers: Record<string, string>
  query?: Record<string, string>
  body?: unknown
  contentType?: string
  multipart?: {
    fields: Record<string, unknown>
    files: Record<string, { originalname: string; mimetype: string; size: number; buffer: Buffer } | Array<{ originalname: string; mimetype: string; size: number; buffer: Buffer }>>
  }
}
export const parseRouteParams = (path: string): string[] => {
  const params: string[] = []
  const segments = path.split('/')
  for (const segment of segments) {
    if (segment.startsWith(':')) {
      params.push(segment.slice(1))
    } else if (segment.startsWith('{') && segment.endsWith('}')) {
      params.push(segment.slice(1, -1))
    }
  }
  return params
}
const extractBodyParams = (
  data: Record<string, unknown>,
  bodySchema: Record<string, unknown>
): Record<string, unknown> => {
  const properties = bodySchema.properties as Record<string, Record<string, unknown>> | undefined
  if (!properties) return data
  const body: Record<string, unknown> = {}
  for (const key of Object.keys(properties)) {
    if (key in data) {
      const propSchema = properties[key]
      if (propSchema?.type === 'object' && propSchema.properties) {
        body[key] = extractBodyParams(data, propSchema)
      } else {
        body[key] = data[key]
      }
    }
  }
  return body
}
const extractQueryParams = (
  data: Record<string, unknown>,
  querySchema: Record<string, unknown>
): Record<string, string> => {
  const properties = querySchema.properties as Record<string, Record<string, unknown>> | undefined
  if (!properties) return {}
  const query: Record<string, string> = {}
  for (const key of Object.keys(properties)) {
    if (key in data) {
      query[key] = String(data[key])
    }
  }
  return query
}
const extractRemainingParams = (
  data: Record<string, unknown>,
  pathParams: string[],
  body?: Record<string, unknown>
): Record<string, string> => {
  const usedKeys = new Set(pathParams)
  if (body) {
    Object.keys(body).forEach((k) => usedKeys.add(k))
  }
  const query: Record<string, string> = {}
  for (const [key, value] of Object.entries(data)) {
    if (!usedKeys.has(key)) {
      query[key] = String(value)
    }
  }
  return query
}
const PARAM_PATTERN = /:([a-zA-Z_][a-zA-Z0-9_]*)/g
const validateParamName = (paramName: string): void => {
  if (!/^[a-zA-Z_][a-zA-Z0-9_]*$/.test(paramName)) {
    throw new Error(`Invalid path parameter name: ${paramName}. Must match /^[a-zA-Z_][a-zA-Z0-9_]*$/`)
  }
}
/**
 * Infer resource type from path parameter name.
 * Supports patterns like: tenantId → tenant, user_id → user, id → resource
 */
const inferResourceTypeFromParam = (param: string): string | null => {
  // Pattern: tenantId, projectId, userId → tenant, project, user
  if (param.endsWith('Id')) {
    return param.replace(/Id$/, '').toLowerCase()
  }
  // Pattern: tenant_id, user_id → tenant, user
  if (param.endsWith('_id')) {
    return param.replace(/_id$/, '').toLowerCase()
  }
  // Pattern: just 'id' — infer from context or return null
  if (param === 'id') {
    return null // Can't infer from just 'id'
  }
  return null
}
const sanitizeParamValue = (value: unknown): string => {
  const str = String(value)
  // URL-encode the value to prevent injection
  return encodeURIComponent(str)
}
const substitutePathParams = (
  path: string,
  data: Record<string, unknown>,
  state: ModelState,
  rng?: SeededRng
): string => {
  let url = path
  const pathParams = parseRouteParams(path)
  for (const param of pathParams) {
    // Validate param name against whitelist
    validateParamName(param)
    let value = data[param]
    // If param is an ID reference, try to find it in state
    if (value === undefined) {
      // Try various patterns: tenantId, tenant_id, id, userId, etc.
      const resourceType = inferResourceTypeFromParam(param)
      if (resourceType) {
        const resources = state.resources.get(resourceType)
        if (resources && resources.size > 0) {
          const ids = Array.from(resources.keys())
          value = rng ? rng.pick(ids) : ids[0] // Deterministic fallback: use first ID
        }
      }
    }
    if (value !== undefined) {
      // Sanitize value before substitution to prevent injection
      url = url.replace(`:${param}`, sanitizeParamValue(value))
    }
  }
  return url
}
const buildHeaders = (
  route: RouteContract,
  scopeHeaders: Record<string, string>,
  data: Record<string, unknown>,
  _state: ModelState
): Record<string, string> => {
  const headers: Record<string, string> = { ...scopeHeaders }
  // Content-Type for body requests
  if (route.schema?.body) {
    headers['content-type'] = CONTENT_TYPE.JSON
  }
  return headers
}
const getString = (obj: Record<string, unknown>, key: string): string | undefined => {
  const val = obj[key]
  return typeof val === 'string' ? val : undefined
}
export const buildRequest = (
  route: RouteContract,
  generatedData: Record<string, unknown>,
  scopeHeaders: Record<string, string>,
  state: ModelState,
  rng?: SeededRng
): RequestStructure => {
  const url = substitutePathParams(route.path, generatedData, state, rng)
  // Extract body params from schema
  const bodySchema = route.schema?.body as Record<string, unknown> | undefined
  // Check for multipart
  const isMultipart = bodySchema && getString(bodySchema, 'x-content-type') === CONTENT_TYPE.MULTIPART
  if (isMultipart) {
    const multipartData = (generatedData ?? {}) as Record<string, unknown>
    const headers = buildHeaders(route, scopeHeaders, generatedData, state)
    headers['content-type'] = CONTENT_TYPE.MULTIPART
    const files = multipartData['files']
    const fields = multipartData['fields']
    return {
      method: route.method,
      url,
      headers,
      query: extractRemainingParams(generatedData, parseRouteParams(route.path)),
      multipart: {
        fields: (fields ?? {}) as Record<string, unknown>,
        files: (files ?? {}) as NonNullable<RequestStructure['multipart']>['files'],
      },
      contentType: CONTENT_TYPE.MULTIPART,
    }
  }
  const body = bodySchema
    ? extractBodyParams(generatedData, bodySchema)
    : undefined
  // Extract query params from schema
  const querySchema = route.schema?.querystring as Record<string, unknown> | undefined
  const query = querySchema
    ? extractQueryParams(generatedData, querySchema)
    : extractRemainingParams(generatedData, parseRouteParams(route.path), body)
  // Build headers
  const headers = buildHeaders(route, scopeHeaders, generatedData, state)
  // Determine content type
  const contentType = body ? CONTENT_TYPE.JSON : undefined
  return { method: route.method, url, headers, query, body, contentType }
}
export const extractPathParams = (routePath: string, url: string): Record<string, unknown> => {
  const routeSegments = routePath.split('/').filter(Boolean)
  const urlSegments = url.split('/').filter(Boolean)
  const params: Record<string, unknown> = {}
  for (let i = 0; i < routeSegments.length; i++) {
    const routeSeg = routeSegments[i]
    const urlSeg = urlSegments[i]
    if (routeSeg?.startsWith(':')) {
      params[routeSeg.slice(1)] = urlSeg
    } else if (routeSeg?.startsWith('{') && routeSeg.endsWith('}')) {
      params[routeSeg.slice(1, -1)] = urlSeg
    }
  }
  return params
}