import { AgentName, AutonomyLevel, ModelProfile } from "../types/config.js";
import { AgentContext } from "../agents/base.js";
import { Decision } from "../types/decisions.js";
import { Escalation } from "../types/escalation.js";

export type BackendType = "llm" | "agent";

export interface BackendRequest {
  persona: AgentName;
  workflow: string;
  task: string;
  context: AgentContext;
  autonomy: AutonomyLevel;
}

export interface Artifact {
  path: string;
  content: string;
  operation: "create" | "update" | "delete";
}

export interface TokenUsage {
  input_tokens: number;
  output_tokens: number;
  total_tokens: number;
  estimated_cost_usd: number;
}

export interface BackendResult {
  success: boolean;
  output: string;
  artifacts: Artifact[];
  decisions: Decision[];
  escalations: Escalation[];
  usage: TokenUsage;
  error?: string;
}

export interface IntelligenceBackend {
  readonly name: string;
  readonly type: BackendType;
  isAvailable(): Promise<boolean>;
  execute(request: BackendRequest): Promise<BackendResult>;
}

export interface LLMBackendConfig {
  base_url: string;
  model_profile: ModelProfile;
  model?: string;
  timeout_ms?: number;
}

export interface OllamaLocalConfig extends LLMBackendConfig {
  base_url: string;
  model_profile: ModelProfile;
  model?: string;
  timeout_ms?: number;
}

export interface OllamaCloudConfig extends LLMBackendConfig {
  base_url: string;
  api_key_env: string;
  model_profile: ModelProfile;
  model?: string;
  timeout_ms?: number;
}

export interface OpencodeBackendConfig {
  enabled: boolean;
  executable?: string;
}

export interface BackendConfigSection {
  provider: "auto" | "opencode" | "ollama-local" | "ollama-cloud";
  fallback?: "opencode" | "ollama-local" | "ollama-cloud";
  agent_backends: {
    opencode?: OpencodeBackendConfig;
  };
  llm_backends: {
    "ollama-local"?: OllamaLocalConfig;
    "ollama-cloud"?: OllamaCloudConfig;
  };
}

export const DEFAULT_BACKEND_CONFIG: BackendConfigSection = {
  provider: "auto",
  agent_backends: {
    opencode: { enabled: true },
  },
  llm_backends: {
    "ollama-local": {
      base_url: "http://localhost:11434",
      model_profile: "balanced",
    },
    "ollama-cloud": {
      base_url: "",
      api_key_env: "OLLAMA_CLOUD_API_KEY",
      model_profile: "quality",
      timeout_ms: 60000,
    },
  },
};

export class BackendUnavailableError extends Error {
  readonly backendName: string;
  readonly agentName?: string;

  constructor(backendName: string, agentName?: string) {
    const agentMsg = agentName ? ` (agent: ${agentName})` : "";
    super(
      `Intelligence backend "${backendName}" is not available${agentMsg}. ` +
      `Configure one of:\n` +
      `  1. Install opencode: npm i -g opencode\n` +
      `  2. Run Ollama locally: ollama serve\n` +
      `  3. Set OLLAMA_CLOUD_API_KEY for remote inference`
    );
    this.name = "BackendUnavailableError";
    this.backendName = backendName;
    this.agentName = agentName;
  }
}

export function emptyTokenUsage(): TokenUsage {
  return { input_tokens: 0, output_tokens: 0, total_tokens: 0, estimated_cost_usd: 0 };
}

export function emptyBackendResult(error?: string): BackendResult {
  return {
    success: false,
    output: "",
    artifacts: [],
    decisions: [],
    escalations: [],
    usage: emptyTokenUsage(),
    error,
  };
}