/**
 * Gemini Integration for Product OS
 * 
 * Supports:
 * - Chat completions with streaming
 * - Tool/function calling
 * - Context-aware responses
 * 
 * Set GOOGLE_CLOUD_PROJECT and optionally GEMINI_MODEL env vars.
 * For local dev without Vertex AI, set GEMINI_API_KEY for AI Studio.
 */

import { config } from "./config.js";

export interface ChatMessage {
  role: "user" | "assistant" | "system";
  content: string;
}

export interface ToolCall {
  name: string;
  arguments: Record<string, any>;
}

export interface ChatResponse {
  message: string;
  toolCalls?: ToolCall[];
  finishReason: "stop" | "tool_calls" | "error";
}

// Tool definitions that Gemini can call
export const PRODUCT_OS_TOOLS = [
  {
    name: "deploy_service",
    description: "Deploy a Cloud Run service. Use when user wants to deploy, ship, or launch code.",
    parameters: {
      type: "object",
      properties: {
        service_name: { type: "string", description: "Name of the service to deploy" },
        repo: { type: "string", description: "Git repository URL" },
        ref: { type: "string", description: "Git branch, tag, or commit" },
        env: { type: "string", enum: ["dev", "staging", "prod"], description: "Target environment" }
      },
      required: ["service_name"]
    }
  },
  {
    name: "get_funnel_analytics",
    description: "Get funnel conversion metrics. Use when user asks about funnels, conversions, or drop-offs.",
    parameters: {
      type: "object",
      properties: {
        range_days: { type: "integer", description: "Number of days to analyze", default: 30 }
      }
    }
  },
  {
    name: "get_top_drivers",
    description: "Identify top factors driving a metric. Use when user asks why something changed or what drives conversions.",
    parameters: {
      type: "object",
      properties: {
        metric: { type: "string", description: "The metric to analyze (e.g., 'conversion', 'retention')" },
        range_days: { type: "integer", description: "Number of days to analyze", default: 30 }
      },
      required: ["metric"]
    }
  },
  {
    name: "generate_marketing_posts",
    description: "Generate social media posts for a campaign. Use when user wants to create marketing content.",
    parameters: {
      type: "object",
      properties: {
        goal: { type: "string", description: "Campaign goal (e.g., 'launch announcement')" },
        product: { type: "string", description: "Product or feature name" },
        channels: { 
          type: "array", 
          items: { type: "string" },
          description: "Social channels (e.g., ['x', 'linkedin'])" 
        }
      },
      required: ["goal"]
    }
  },
  {
    name: "get_service_status",
    description: "Check the status of a deployed service. Use when user asks about service health or deployment status.",
    parameters: {
      type: "object",
      properties: {
        service_name: { type: "string", description: "Name of the service" },
        region: { type: "string", description: "GCP region", default: "us-central1" }
      },
      required: ["service_name"]
    }
  },
  {
    name: "generate_code",
    description: "Generate or modify code. Use when user asks to write, fix, refactor, or change code.",
    parameters: {
      type: "object",
      properties: {
        task: { type: "string", description: "What code change to make" },
        file_path: { type: "string", description: "Target file path (if known)" },
        language: { type: "string", description: "Programming language" },
        context: { type: "string", description: "Additional context about the codebase" }
      },
      required: ["task"]
    }
  },
  {
    name: "deploy_app",
    description: "Deploy a specific app from the project monorepo. Use when user wants to deploy or ship one of their apps (product, website, admin, storybook).",
    parameters: {
      type: "object",
      properties: {
        project_id: { type: "string", description: "The project ID" },
        app_name: {
          type: "string",
          enum: ["product", "website", "admin", "storybook"],
          description: "Which app to deploy"
        },
        env: {
          type: "string",
          enum: ["dev", "staging", "prod"],
          description: "Target environment"
        }
      },
      required: ["project_id", "app_name"]
    }
  },
  {
    name: "scaffold_app",
    description: "Add a new app to the project monorepo. Use when user wants to add a new application beyond the defaults.",
    parameters: {
      type: "object",
      properties: {
        project_id: { type: "string", description: "The project ID" },
        app_name: { type: "string", description: "Name for the new app (e.g. 'mobile', 'api', 'dashboard')" },
        framework: {
          type: "string",
          enum: ["nextjs", "astro", "express", "fastify"],
          description: "Framework to scaffold"
        }
      },
      required: ["project_id", "app_name"]
    }
  }
];

// System prompt for Product OS assistant
const SYSTEM_PROMPT = `You are the AI for a software platform where every project is a Turborepo monorepo containing multiple apps: product, website, admin, and storybook. You have full visibility and control over the entire project.

Each project has:
- apps/product   — the core user-facing application
- apps/website   — the marketing and landing site
- apps/admin     — internal admin tooling
- apps/storybook — component browser and design system
- packages/ui    — shared React component library
- packages/tokens — shared design tokens (colors, spacing, typography)
- packages/types  — shared TypeScript types
- packages/config — shared eslint and tsconfig

You can help with:
- Deploying any app using turbo run build --filter=<app>
- Writing and modifying code across any app or package in the monorepo
- Adding new apps or packages to the project
- Analyzing product metrics and funnels
- Generating marketing content
- Understanding what drives user behavior

When a user says "deploy" without specifying an app, ask which one or default to "product".
When a user asks to change something visual, consider whether it belongs in packages/ui or packages/tokens.
When users ask you to do something, use the available tools to take action. Be concise and specific about which app or package you are working in.`;

/**
 * Chat with Gemini
 * Uses Vertex AI in production, or AI Studio API key for local dev
 */
export async function chat(
  messages: ChatMessage[],
  options: { stream?: boolean } = {}
): Promise<ChatResponse> {
  const apiKey = process.env.GEMINI_API_KEY;
  const projectId = config.projectId;
  const model = process.env.GEMINI_MODEL ?? "gemini-1.5-flash";

  // Build the request
  const contents = [
    { role: "user", parts: [{ text: SYSTEM_PROMPT }] },
    { role: "model", parts: [{ text: "Understood. I'm Product OS, ready to help you build and operate your SaaS product. How can I help?" }] },
    ...messages.map(m => ({
      role: m.role === "assistant" ? "model" : "user",
      parts: [{ text: m.content }]
    }))
  ];

  const tools = [{
    functionDeclarations: PRODUCT_OS_TOOLS
  }];

  // Use AI Studio API if API key is set (local dev)
  if (apiKey) {
    return chatWithAIStudio(apiKey, model, contents, tools);
  }

  // Use Vertex AI if project is set (production)
  if (projectId && projectId !== "productos-local") {
    return chatWithVertexAI(projectId, model, contents, tools);
  }

  // Mock response for local dev without credentials
  return mockChat(messages);
}

async function chatWithAIStudio(
  apiKey: string,
  model: string,
  contents: any[],
  tools: any[]
): Promise<ChatResponse> {
  const url = `https://generativelanguage.googleapis.com/v1beta/models/${model}:generateContent?key=${apiKey}`;

  const response = await fetch(url, {
    method: "POST",
    headers: { "Content-Type": "application/json" },
    body: JSON.stringify({
      contents,
      tools,
      generationConfig: {
        temperature: 0.7,
        maxOutputTokens: 2048
      }
    })
  });

  if (!response.ok) {
    const error = await response.text();
    console.error("Gemini API error:", error);
    throw new Error(`Gemini API error: ${response.status}`);
  }

  const data = await response.json();
  return parseGeminiResponse(data);
}

async function chatWithVertexAI(
  projectId: string,
  model: string,
  contents: any[],
  tools: any[]
): Promise<ChatResponse> {
  // Vertex AI endpoint
  const location = process.env.VERTEX_LOCATION ?? "us-central1";
  const url = `https://${location}-aiplatform.googleapis.com/v1/projects/${projectId}/locations/${location}/publishers/google/models/${model}:generateContent`;

  // Get access token (requires gcloud auth)
  const { GoogleAuth } = await import("google-auth-library");
  const auth = new GoogleAuth({ scopes: ["https://www.googleapis.com/auth/cloud-platform"] });
  const client = await auth.getClient();
  const token = await client.getAccessToken();

  const response = await fetch(url, {
    method: "POST",
    headers: {
      "Content-Type": "application/json",
      "Authorization": `Bearer ${token.token}`
    },
    body: JSON.stringify({
      contents,
      tools,
      generationConfig: {
        temperature: 0.7,
        maxOutputTokens: 2048
      }
    })
  });

  if (!response.ok) {
    const error = await response.text();
    console.error("Vertex AI error:", error);
    throw new Error(`Vertex AI error: ${response.status}`);
  }

  const data = await response.json();
  return parseGeminiResponse(data);
}

function parseGeminiResponse(data: any): ChatResponse {
  const candidate = data.candidates?.[0];
  if (!candidate) {
    return { message: "No response from Gemini", finishReason: "error" };
  }

  const content = candidate.content;
  const parts = content?.parts ?? [];

  // Check for function calls
  const functionCalls = parts.filter((p: any) => p.functionCall);
  if (functionCalls.length > 0) {
    const toolCalls = functionCalls.map((p: any) => ({
      name: p.functionCall.name,
      arguments: p.functionCall.args ?? {}
    }));
    return {
      message: "",
      toolCalls,
      finishReason: "tool_calls"
    };
  }

  // Regular text response
  const text = parts.map((p: any) => p.text ?? "").join("");
  return {
    message: text,
    finishReason: "stop"
  };
}

/**
 * Mock chat for local development without Gemini credentials
 */
function mockChat(messages: ChatMessage[]): ChatResponse {
  const lastMessage = messages[messages.length - 1]?.content.toLowerCase() ?? "";

  // Check marketing/campaign FIRST (before deploy) since "launch" can be ambiguous
  if (lastMessage.includes("marketing") || lastMessage.includes("campaign") || lastMessage.includes("post") || 
      (lastMessage.includes("launch") && !lastMessage.includes("deploy"))) {
    return {
      message: "",
      toolCalls: [{
        name: "generate_marketing_posts",
        arguments: { goal: "product launch", channels: ["x", "linkedin"] }
      }],
      finishReason: "tool_calls"
    };
  }

  // Simple keyword matching to simulate tool calls
  if (lastMessage.includes("deploy") || lastMessage.includes("ship") || lastMessage.includes("staging") || lastMessage.includes("production")) {
    return {
      message: "",
      toolCalls: [{
        name: "deploy_service",
        arguments: { service_name: "my-service", env: lastMessage.includes("staging") ? "staging" : lastMessage.includes("prod") ? "prod" : "dev" }
      }],
      finishReason: "tool_calls"
    };
  }

  if (lastMessage.includes("funnel") || lastMessage.includes("conversion") || lastMessage.includes("analytics")) {
    return {
      message: "",
      toolCalls: [{
        name: "get_funnel_analytics",
        arguments: { range_days: 30 }
      }],
      finishReason: "tool_calls"
    };
  }

  if (lastMessage.includes("why") || lastMessage.includes("driver") || lastMessage.includes("cause")) {
    return {
      message: "",
      toolCalls: [{
        name: "get_top_drivers",
        arguments: { metric: "conversion", range_days: 30 }
      }],
      finishReason: "tool_calls"
    };
  }

  if (lastMessage.includes("status") || lastMessage.includes("health")) {
    return {
      message: "",
      toolCalls: [{
        name: "get_service_status",
        arguments: { service_name: "my-service" }
      }],
      finishReason: "tool_calls"
    };
  }

  if (lastMessage.includes("code") || lastMessage.includes("function") || lastMessage.includes("write") || lastMessage.includes("create")) {
    return {
      message: "",
      toolCalls: [{
        name: "generate_code",
        arguments: { task: lastMessage, language: "typescript" }
      }],
      finishReason: "tool_calls"
    };
  }

  // Default response
  return {
    message: `I'm Product OS, your AI assistant for building and operating SaaS products. I can help you:

• **Deploy** services to Cloud Run
• **Analyze** funnel metrics and conversions  
• **Generate** marketing content
• **Understand** what drives user behavior

What would you like to do?

_(Note: Running in mock mode - set GEMINI_API_KEY for real AI responses)_`,
    finishReason: "stop"
  };
}