import { GoogleGenAI, Type, createUserContent, createPartFromUri } from "@google/genai";
import { Quiz, Question, AnswerOption, GenerateQuizOptions, ProcessedDocument, AIProvider } from "../types";
import { v4 as uuidv4 } from 'uuid';

const getGeminiClient = (apiKey?: string) => {
  const key = apiKey || process.env.API_KEY;
  if (!key) {
    throw new Error("Gemini API key is missing");
  }
  return new GoogleGenAI({ apiKey: key });
};

const DEFAULT_GEMINI_MODEL = 'gemini-3-flash-preview';

const OPENROUTER_API_URL = 'https://openrouter.ai/api/v1/chat/completions';
const DEFAULT_OPENROUTER_MODEL = 'google/gemini-3-flash-preview';

const OPENAI_API_URL = 'https://api.openai.com/v1/chat/completions';
const DEFAULT_OPENAI_MODEL = 'gpt-5-mini';

const QUIZ_SCHEMA = {
  type: Type.OBJECT,
  properties: {
    title: { type: Type.STRING, description: "A catchy title for the quiz" },
    questions: {
      type: Type.ARRAY,
      items: {
        type: Type.OBJECT,
        properties: {
          text: { type: Type.STRING, description: "The question text" },
          options: {
            type: Type.ARRAY,
            items: {
              type: Type.OBJECT,
              properties: {
                text: { type: Type.STRING },
                isCorrect: { type: Type.BOOLEAN },
                reason: { type: Type.STRING, description: "Brief explanation of why this answer is correct or incorrect" }
              },
              required: ["text", "isCorrect", "reason"]
            },
          }
        },
        required: ["text", "options"]
      }
    }
  },
  required: ["title", "questions"]
};

function buildPrompt(options: GenerateQuizOptions, hasDocuments: boolean, includeJsonExample: boolean = false): string {
  const questionCount = options.questionCount || 10;
  
  let baseInstructions = `Create ${questionCount} engaging multiple-choice questions. Each question must have exactly 4 options, and exactly one correct answer. Vary the difficulty.

IMPORTANT: For each option's reason, write as if you are directly explaining facts - never reference "the document", "the text", "the material", or "the source". Write explanations as standalone factual statements.`;

  if (includeJsonExample) {
    baseInstructions += `

You MUST respond with a single JSON object in this exact structure:
{
  "title": "Quiz Title Here",
  "questions": [
    {
      "text": "Question text here?",
      "options": [
        { "text": "Option A", "isCorrect": false, "reason": "Explanation why this is wrong" },
        { "text": "Option B", "isCorrect": true, "reason": "Explanation why this is correct" },
        { "text": "Option C", "isCorrect": false, "reason": "Explanation why this is wrong" },
        { "text": "Option D", "isCorrect": false, "reason": "Explanation why this is wrong" }
      ]
    }
  ]
}

Return ONLY valid JSON with no additional text before or after.`;
  }

  if (hasDocuments) {
    const topicContext = options.topic 
      ? ` Focus on aspects related to "${options.topic}".` 
      : '';
    return `Generate a quiz based on the provided content.${topicContext}

${baseInstructions}`;
  }
  
  return `Generate a trivia quiz about "${options.topic}".

${baseInstructions}`;
}

function shuffleArray<T>(array: T[]): T[] {
  const shuffled = [...array];
  for (let i = shuffled.length - 1; i > 0; i--) {
    const j = Math.floor(Math.random() * (i + 1));
    [shuffled[i], shuffled[j]] = [shuffled[j], shuffled[i]];
  }
  return shuffled;
}

function transformToQuiz(data: any): Quiz {
  const shapes = ['triangle', 'diamond', 'circle', 'square'] as const;
  const colors = ['red', 'blue', 'yellow', 'green'] as const;
  
  const questions: Question[] = data.questions.map((q: any) => {
    const shuffledOpts = shuffleArray(q.options);
    
    const options: AnswerOption[] = shuffledOpts.map((opt: any, index: number) => ({
      text: opt.text,
      isCorrect: opt.isCorrect,
      shape: shapes[index % 4],
      color: colors[index % 4],
      reason: opt.reason
    }));

    return {
      id: uuidv4(),
      text: q.text,
      options: options,
      timeLimit: 20
    };
  });

  return {
    title: data.title,
    questions
  };
}

async function uploadNativeDocument(ai: GoogleGenAI, doc: ProcessedDocument): Promise<{ uri: string; mimeType: string }> {
  const buffer = typeof doc.content === 'string'
    ? Buffer.from(doc.content, 'base64')
    : doc.content;
  
  const blob = new Blob([buffer], { type: doc.mimeType });
  
  const uploadedFile = await ai.files.upload({
    file: blob,
    config: { mimeType: doc.mimeType! }
  });
  
  if (!uploadedFile.uri || !uploadedFile.mimeType) {
    throw new Error("Failed to upload document to Gemini");
  }
  
  return { uri: uploadedFile.uri, mimeType: uploadedFile.mimeType };
}

const JSON_SCHEMA_FOR_OPENROUTER = {
  type: "object",
  properties: {
    title: { type: "string", description: "A catchy title for the quiz" },
    questions: {
      type: "array",
      items: {
        type: "object",
        properties: {
          text: { type: "string", description: "The question text" },
          options: {
            type: "array",
            items: {
              type: "object",
              properties: {
                text: { type: "string" },
                isCorrect: { type: "boolean" },
                reason: { type: "string", description: "Brief explanation of why this answer is correct or incorrect" }
              },
              required: ["text", "isCorrect", "reason"]
            },
          }
        },
        required: ["text", "options"]
      }
    }
  },
  required: ["title", "questions"]
};

const JSON_SCHEMA_FOR_OPENAI = {
  type: "object",
  properties: {
    title: { type: "string", description: "A catchy title for the quiz" },
    questions: {
      type: "array",
      items: {
        type: "object",
        properties: {
          text: { type: "string", description: "The question text" },
          options: {
            type: "array",
            items: {
              type: "object",
              properties: {
                text: { type: "string" },
                isCorrect: { type: "boolean" },
                reason: { type: "string", description: "Brief explanation of why this answer is correct or incorrect" }
              },
              required: ["text", "isCorrect", "reason"],
              additionalProperties: false
            },
          }
        },
        required: ["text", "options"],
        additionalProperties: false
      }
    }
  },
  required: ["title", "questions"],
  additionalProperties: false
};

async function generateQuizWithGemini(options: GenerateQuizOptions): Promise<Quiz> {
  const ai = getGeminiClient(options.apiKey);
  
  const docs = options.documents || [];
  const hasDocuments = docs.length > 0;
  const prompt = buildPrompt(options, hasDocuments);
  
  let contents: any;
  
  if (hasDocuments) {
    const parts: any[] = [];
    
    for (const doc of docs) {
      if (doc.type === 'native' && doc.mimeType) {
        const uploaded = await uploadNativeDocument(ai, doc);
        parts.push(createPartFromUri(uploaded.uri, uploaded.mimeType));
      } else if (doc.type === 'text') {
        parts.push({ text: doc.content as string });
      }
    }
    
    parts.push({ text: prompt });
    contents = createUserContent(parts);
  } else {
    contents = prompt;
  }

  const model = options.geminiModel || DEFAULT_GEMINI_MODEL;
  
  const response = await ai.models.generateContent({
    model,
    contents,
    config: {
      responseMimeType: "application/json",
      responseSchema: QUIZ_SCHEMA
    }
  });

  if (!response.text) {
    throw new Error("Failed to generate quiz content");
  }

  const data = JSON.parse(response.text);
  return transformToQuiz(data);
}

async function generateQuizWithOpenRouter(options: GenerateQuizOptions): Promise<Quiz> {
  const apiKey = options.apiKey;
  if (!apiKey) {
    throw new Error("OpenRouter API key is missing");
  }

  const docs = options.documents || [];
  const hasDocuments = docs.length > 0;
  const prompt = buildPrompt(options, hasDocuments, true);
  
  let fullPrompt = prompt;
  
  // For OpenRouter, we can't upload files directly - include text content in the prompt
  if (hasDocuments) {
    const textParts: string[] = [];
    for (const doc of docs) {
      if (doc.type === 'text') {
        textParts.push(doc.content as string);
      } else if (doc.type === 'native') {
        // For native documents, they should have been converted to text on the backend
        // If not, skip them with a warning
        console.warn('Native document type not supported with OpenRouter - document will be skipped');
      }
    }
    
    if (textParts.length > 0) {
      fullPrompt = `Here is the content to create a quiz from:\n\n${textParts.join('\n\n---\n\n')}\n\n${prompt}`;
    }
  }

  const model = options.openRouterModel || DEFAULT_OPENROUTER_MODEL;
  
  const response = await fetch(OPENROUTER_API_URL, {
    method: 'POST',
    headers: {
      'Authorization': `Bearer ${apiKey}`,
      'Content-Type': 'application/json',
      'HTTP-Referer': window.location.origin,
      'X-Title': 'Kaboot Quiz Generator',
    },
    body: JSON.stringify({
      model,
      messages: [
        {
          role: 'user',
          content: fullPrompt
        }
      ],
      response_format: {
        type: 'json_schema',
        json_schema: {
          name: 'quiz',
          strict: true,
          schema: JSON_SCHEMA_FOR_OPENROUTER
        }
      }
    })
  });

  if (!response.ok) {
    const error = await response.json().catch(() => ({ error: { message: 'Unknown error' } }));
    throw new Error(error.error?.message || `OpenRouter API error: ${response.status}`);
  }

  const result = await response.json();
  const content = result.choices?.[0]?.message?.content;
  
  // console.log('[OpenRouter] Raw response:', content);
  
  if (!content) {
    throw new Error("Failed to generate quiz content from OpenRouter");
  }

  const data = JSON.parse(content);
  return transformToQuiz(data);
}

async function generateQuizWithOpenAI(options: GenerateQuizOptions): Promise<Quiz> {
  const apiKey = options.apiKey;
  if (!apiKey) {
    throw new Error("OpenAI API key is missing");
  }

  const docs = options.documents || [];
  const hasDocuments = docs.length > 0;
  const prompt = buildPrompt(options, hasDocuments, true);
  
  let fullPrompt = prompt;
  
  if (hasDocuments) {
    const textParts: string[] = [];
    for (const doc of docs) {
      if (doc.type === 'text') {
        textParts.push(doc.content as string);
      } else if (doc.type === 'native') {
        console.warn('Native document type not supported with OpenAI - document will be skipped');
      }
    }
    
    if (textParts.length > 0) {
      fullPrompt = `Here is the content to create a quiz from:\n\n${textParts.join('\n\n---\n\n')}\n\n${prompt}`;
    }
  }

  const model = options.openAIModel || DEFAULT_OPENAI_MODEL;
  
  const response = await fetch(OPENAI_API_URL, {
    method: 'POST',
    headers: {
      'Authorization': `Bearer ${apiKey}`,
      'Content-Type': 'application/json',
    },
    body: JSON.stringify({
      model,
      messages: [
        {
          role: 'user',
          content: fullPrompt
        }
      ],
      response_format: {
        type: 'json_schema',
        json_schema: {
          name: 'quiz',
          strict: true,
          schema: JSON_SCHEMA_FOR_OPENAI
        }
      }
    })
  });

  if (!response.ok) {
    const error = await response.json().catch(() => ({ error: { message: 'Unknown error' } }));
    throw new Error(error.error?.message || `OpenAI API error: ${response.status}`);
  }

  const result = await response.json();
  const content = result.choices?.[0]?.message?.content;
  
  // console.log('[OpenAI] Raw response:', content);
  
  if (!content) {
    throw new Error("Failed to generate quiz content from OpenAI");
  }

  const data = JSON.parse(content);
  return transformToQuiz(data);
}

const API_URL = import.meta.env.VITE_API_URL || '';

async function generateQuizWithServer(options: GenerateQuizOptions): Promise<Quiz> {
  if (!options.accessToken) {
    throw new Error("Authentication required for system AI");
  }

  const docs = options.documents || [];
  const documentsPayload = docs.map(doc => ({
    type: doc.type,
    content: doc.type === 'native' && doc.content instanceof ArrayBuffer
      ? btoa(String.fromCharCode(...new Uint8Array(doc.content)))
      : doc.content,
    mimeType: doc.mimeType
  }));

  const response = await fetch(`${API_URL}/api/generate`, {
    method: 'POST',
    headers: {
      'Authorization': `Bearer ${options.accessToken}`,
      'Content-Type': 'application/json',
    },
    body: JSON.stringify({
      topic: options.topic,
      questionCount: options.questionCount || 10,
      documents: documentsPayload
    })
  });

  if (!response.ok) {
    const error = await response.json().catch(() => ({ error: 'Unknown error' }));
    throw new Error(error.error || `Server error: ${response.status}`);
  }

  return response.json();
}

export async function checkSystemAIAvailable(): Promise<boolean> {
  try {
    const response = await fetch(`${API_URL}/api/generate/status`);
    if (!response.ok) return false;
    const data = await response.json();
    return data.available === true;
  } catch {
    return false;
  }
}

export const generateQuiz = async (options: GenerateQuizOptions): Promise<Quiz> => {
  const provider = options.aiProvider || 'gemini';
  
  if (provider === 'system') {
    return generateQuizWithServer(options);
  }
  
  if (provider === 'openrouter') {
    return generateQuizWithOpenRouter(options);
  }
  
  if (provider === 'openai') {
    return generateQuizWithOpenAI(options);
  }
  
  return generateQuizWithGemini(options);
};