/**
 * AnthropicAdapter - Provider adapter for Anthropic API
 *
 * Implements ProviderAdapter contract (contracts §15); DD §12.2.
 *
 * @module packages/llm/src/adapters/AnthropicAdapter
 */

import type {
  ModelID,
  ProviderAdapter,
  ProviderCapabilityMatrix,
  ProviderCompletionInput,
  ProviderID,
  ProviderStreamEvent,
} from '@aircoding/contracts'

import { AnthropicCanonicalConverter } from '../canonical/AnthropicCanonical.js'

export interface AnthropicConfig {
  api_key?: string
  base_url?: string
  max_retries?: number
  timeout?: number
}

interface AnthropicApiResponse {
  id: string
  type: string
  role: string
  content: Array<{ type: string; text?: string; thinking?: string; id?: string; name?: string; input?: unknown }>
  stop_reason?: string
  usage?: { input_tokens: number; output_tokens: number }
}

interface AnthropicApiRequest {
  model: string
  messages: Array<{ role: string; content: Array<Record<string, unknown>> }>
  max_tokens: number
  temperature?: number
  top_p?: number
  system?: string
  stream?: boolean
}

export class AnthropicAdapter implements ProviderAdapter {
  readonly provider_id: ProviderID = 'anthropic'
  private api_key: string
  private base_url: string
  private max_retries: number
  private timeout: number
  private converter: AnthropicCanonicalConverter

  constructor(config: AnthropicConfig = {}) {
    this.api_key = config.api_key || process.env.ANTHROPIC_API_KEY || ''
    this.base_url = config.base_url || process.env.ANTHROPIC_BASE_URL || 'https://api.anthropic.com'
    this.max_retries = config.max_retries || 3
    this.timeout = config.timeout || 60000
    this.converter = new AnthropicCanonicalConverter()
  }

  /**
   * Known Anthropic models.
   */
  private static readonly KNOWN_MODELS: Array<{
    model_id: string
    display_name: string
    family: 'claude-opus' | 'claude-sonnet' | 'claude-haiku'
  }> = [
    { model_id: 'claude-opus-4-7-20251119', display_name: 'Claude Opus 4.7', family: 'claude-opus' },
    { model_id: 'claude-sonnet-4-6-20250501', display_name: 'Claude Sonnet 4.6', family: 'claude-sonnet' },
    { model_id: 'claude-haiku-4-5-20251001', display_name: 'Claude Haiku 4.5', family: 'claude-haiku' },
  ]

  async list_models(): Promise<ProviderCapabilityMatrix[]> {
    return AnthropicAdapter.KNOWN_MODELS.map(m => this.capability_matrix(m.model_id, m.display_name, m.family))
  }

  async validate_model(model_id: ModelID): Promise<ProviderCapabilityMatrix> {
    const known = AnthropicAdapter.KNOWN_MODELS.find(m => m.model_id === model_id)
    if (known) {
      return this.capability_matrix(known.model_id, known.display_name, known.family)
    }
    // Allow any model that looks like a Claude model (flexible acceptance)
    if (String(model_id).startsWith('claude-')) {
      return this.capability_matrix(String(model_id), `Custom Claude ${model_id}`, 'claude-sonnet')
    }
    throw new Error(`Unknown Anthropic model: ${model_id}`)
  }

  /**
   * Execute a completion request (implements ProviderAdapter.complete).
   * Returns an AsyncIterable of ProviderStreamEvent ({type, payload}).
   */
  async *complete(input: ProviderCompletionInput): AsyncIterable<ProviderStreamEvent> {
    const messages = this.convert_to_anthropic_messages(input.messages as { role: string; content: unknown }[])
    const response = await this.make_request({
      model: String(input.model_id),
      messages,
      max_tokens: input.max_output_tokens ?? 4096,
      temperature: input.temperature,
      system: input.system as string | undefined,
      stream: false,
    })

    // Yield each content block as an event
    yield { type: 'message_start', payload: { id: response.id, role: response.role } }
    for (const block of response.content) {
      if (block.type === 'text' && block.text) {
        yield { type: 'content_delta', payload: { type: 'text_delta', text: block.text } }
      } else if (block.type === 'thinking' && block.thinking) {
        yield { type: 'content_delta', payload: { type: 'thinking_delta', thinking: block.thinking } }
      }
    }
    if (response.usage) {
      yield {
        type: 'message_stop',
        payload: { stop_reason: response.stop_reason || 'end_turn', usage: { output_tokens: response.usage.output_tokens } }
      }
    } else {
      yield { type: 'message_stop', payload: { stop_reason: 'end_turn' } }
    }
  }

  /**
   * Backward-compat: single-shot complete that returns string content.
   * Used by MainAgent.classify_via_llm.
   */
  async complete_text(messages: unknown[], options: { model?: string; max_tokens?: number } = {}): Promise<{ content: string; usage?: { input_tokens: number; output_tokens: number } }> {
    const response = await this.make_request({
      model: options.model || 'claude-haiku-4-5-20251001',
      messages: this.convert_raw_messages(messages),
      max_tokens: options.max_tokens || 1024,
      stream: false,
    })
    return {
      content: this.extract_content(response),
      usage: response.usage ? { input_tokens: response.usage.input_tokens, output_tokens: response.usage.output_tokens } : undefined,
    }
  }

  private convert_to_anthropic_messages(messages: Array<{ role: string; content: unknown }>): Array<{ role: string; content: Array<Record<string, unknown>> }> {
    return messages.map(m => {
      const blocks: Array<Record<string, unknown>> = []
      if (typeof m.content === 'string') {
        blocks.push({ type: 'text', text: m.content })
      } else if (Array.isArray(m.content)) {
        for (const c of m.content) {
          if (typeof c === 'string') blocks.push({ type: 'text', text: c })
          else blocks.push(c as Record<string, unknown>)
        }
      }
      return { role: m.role, content: blocks }
    })
  }

  private convert_raw_messages(messages: unknown[]): Array<{ role: string; content: Array<Record<string, unknown>> }> {
    return messages.map(m => {
      const obj = m as { role: string; content: unknown }
      if (typeof obj.content === 'string') {
        return { role: obj.role, content: [{ type: 'text', text: obj.content }] }
      }
      if (Array.isArray(obj.content)) {
        return { role: obj.role, content: obj.content as Array<Record<string, unknown>> }
      }
      return { role: obj.role, content: [{ type: 'text', text: String(obj.content) }] }
    })
  }

  private extract_content(response: AnthropicApiResponse): string {
    return response.content
      .filter(b => b.type === 'text')
      .map(b => b.text || '')
      .join('')
  }

  private capability_matrix(model_id: string, display_name: string, family: string): ProviderCapabilityMatrix {
    return {
      provider_id: this.provider_id,
      model_id: model_id as ModelID,
      display_name,
      
      max_output_tokens: 200000,
      provider_kind: 'anthropic',
      enabled: true,
      quality_tier: 'frontier',
      cost_tier: 'high',
      conversion: { from_anthropic_canonical: 'lossless' as const, tool_schema: 'native' as const, image_input: 'native' as const, thinking: 'native' as const, cache_control: 'native' as const },
      supports: {
        text_input: true,
        text_output: true,
        streaming: true,
        tool_use: true,
        parallel_tool_use: true,
        structured_output: true,
        json_mode: true,
        thinking: family === 'claude-opus' || family === 'claude-sonnet',
        prompt_cache: true,
        system_prompt: true,
        image_input: true,
        image_output: false,
        audio_input: false,
        audio_output: false,
        file_input: true,
        computer_use: false,
        long_context: true,
        batch: false,
      },
    }
  }

  private async make_request(body: AnthropicApiRequest): Promise<AnthropicApiResponse> {
    const response = await fetch(`${this.base_url}/v1/messages`, {
      method: 'POST',
      headers: {
        'Content-Type': 'application/json',
        'x-api-key': this.api_key,
        'anthropic-version': '2023-06-01',
      },
      body: JSON.stringify(body),
    })

    if (!response.ok) {
      const error = await response.text()
      throw new Error(`Anthropic API error: ${response.status} - ${error}`)
    }

    return response.json() as Promise<AnthropicApiResponse>
  }
}

export function createAnthropicAdapter(config?: AnthropicConfig): AnthropicAdapter {
  return new AnthropicAdapter(config)
}

// Backward-compat export
export type AnthropicStreamEvent = ProviderStreamEvent
export type { CanonicalMessage } from '../canonical/AnthropicCanonical.js'