import {z} from 'zod'

export type TextBlock = {type: 'text', text: string};

export type ToolUseBlock = {type: 'tool_use', id: string, name: string, input: {[key: string]: unknown}};

export type ToolResultBlock = {type: 'tool_result', tool_use_id: string, content: string | Array<TextBlock>, is_error?: boolean | undefined};

export type InputMessage = {role: 'user' | 'assistant', content: string | Array<TextBlock | ToolUseBlock | ToolResultBlock>};

export type ToolDefinition = {name: string, description?: string | undefined, input_schema: {[key: string]: unknown}};

export type ToolChoice = {type: 'auto', disable_parallel_tool_use?: boolean | undefined} | {type: 'any'} | {type: 'tool', name: string} | {type: 'none'};

export type MessagesRequest = {model: string, messages: Array<InputMessage>, max_tokens: number, system?: (string | Array<TextBlock>) | undefined, temperature?: number | undefined, top_p?: number | undefined, top_k?: number | undefined, stop_sequences?: Array<string> | undefined, stream?: boolean | undefined, tools?: Array<ToolDefinition> | undefined, tool_choice?: ToolChoice | undefined, metadata?: ({user_id?: string | undefined}) | undefined};

export type CreateApiV1MessagesArgs = {body: MessagesRequest};

export type CreateApiV1MessagesOptions = {baseUrl: string, BearerAuth?: string | undefined, fetch?: typeof fetch | undefined};

export const textBlock = z.object({type: z.literal("text"), text: z.string()});

export const toolUseBlock = z.object({type: z.literal("tool_use"), id: z.string(), name: z.string(), input: z.record(z.string(), z.unknown())});

export const usage = z.object({input_tokens: z.number().int().optional(), output_tokens: z.number().int().optional(), cache_read_input_tokens: z.number().int().optional()}).and(z.record(z.string(), z.unknown()));

export const messagesResponse = z.object({id: z.string(), type: z.literal("message"), role: z.literal("assistant"), content: z.array(z.union([textBlock, toolUseBlock])), model: z.string(), stop_reason: z.enum(["end_turn", "max_tokens", "stop_sequence", "tool_use"]), stop_sequence: z.string().nullable().optional(), usage: usage});

export const validateResponse = async <Output>(
  schema: {
    readonly '~standard': {
      readonly validate: (value: unknown) => ({ readonly value: Output; readonly issues?: undefined } | { readonly issues: ReadonlyArray<{ readonly message: string; readonly path?: ReadonlyArray<PropertyKey | { readonly key: PropertyKey }> | undefined }> }) | Promise<{ readonly value: Output; readonly issues?: undefined } | { readonly issues: ReadonlyArray<{ readonly message: string; readonly path?: ReadonlyArray<PropertyKey | { readonly key: PropertyKey }> | undefined }> }>
    }
  },
  value: unknown
): Promise<Output> => {
  const result = await schema['~standard'].validate(value)

  if (result.issues !== undefined) {
    const detail = result.issues
      .map(({ message, path }) =>
        path?.length
          ? `${path.map((segment) => String(typeof segment === 'object' ? segment.key : segment)).join('.')}: ${message}`
          : message
      )
      .join('; ')

    throw new Error(`Response does not match the schema: ${detail}`, { cause: { issues: result.issues } })
  }

  return result.value
};

/**
 * Create a message
 * 
 * POST /v1/messages
 */
export const createApiV1Messages = async (args: CreateApiV1MessagesArgs, options: CreateApiV1MessagesOptions) => {
const {baseUrl, fetch: fetchFn = fetch, BearerAuth} = options ?? {}

const query = new URLSearchParams()
const headers = new Headers()
headers.set('content-type', "application/json")
headers.set('accept', "application/json")

if (BearerAuth !== undefined) headers.set('authorization', `Bearer ${BearerAuth}`)

const url = `${baseUrl.replace(/\/+$/, '')}/v1/messages${query.size > 0 ? `?${query}` : ''}`

const res = await fetchFn(url, {method: "POST", headers, body: JSON.stringify(args.body)})

if (!res.ok) throw new Error(`Request failed with status ${res.status}`, {cause: {status: res.status, body: await res.text()}})

return validateResponse(messagesResponse, await res.json())
};