package ai

import (
	"bytes"
	"encoding/base64"
	"encoding/json"
	"fmt"
	"io"
	"log"
	"net/http"
	"os"
	"strings"
	"time"
)

const ollamaTimeout = 60 * time.Second

type ollamaRequest struct {
	Model    string          `json:"model"`
	Messages []ollamaMessage `json:"messages"`
	Stream   bool            `json:"stream"`
	Options  map[string]any  `json:"options,omitempty"`
}

type ollamaMessage struct {
	Role    string   `json:"role"`
	Content string   `json:"content"`
	Images  []string `json:"images,omitempty"`
}

type ollamaResponse struct {
	Message struct {
		Content string `json:"content"`
	} `json:"message"`
	Error string `json:"error,omitempty"`
}

type ollamaProvider struct{}

func (p *ollamaProvider) ExtractReceipt(imagePath string) (*ReceiptData, error) {
	imageData, err := readFile(imagePath)
	if err != nil {
		return &ReceiptData{}, fmt.Errorf("read file: %w", err)
	}

	baseURL := os.Getenv("AI_BASE_URL")
	if baseURL == "" {
		baseURL = "http://localhost:11434"
	}
	baseURL = strings.TrimRight(baseURL, "/")

	model := os.Getenv("AI_MODEL")
	if model == "" {
		model = "llava"
	}

	b64Data := base64.StdEncoding.EncodeToString(imageData)

	payload := ollamaRequest{
		Model:  model,
		Stream: false,
		Messages: []ollamaMessage{{
			Role:    "user",
			Content: "Analyze this receipt image. Extract the following fields as a strict JSON object with these exact keys: \"merchant\" (string), \"amount\" (number), \"currency\" (string, 3-letter code), \"category\" (string, one of: Food, Travel, Lodging, Software, Other), \"date\" (string, YYYY-MM-DD). Return ONLY valid JSON. No markdown.",
			Images:  []string{b64Data},
		}},
	}

	body, _ := json.Marshal(payload)
	apiURL := baseURL + "/api/chat"
	req, _ := http.NewRequest(http.MethodPost, apiURL, bytes.NewReader(body))
	req.Header.Set("Content-Type", "application/json")

	client := &http.Client{Timeout: ollamaTimeout}
	resp, err := client.Do(req)
	if err != nil {
		return &ReceiptData{}, fmt.Errorf("Ollama request: %w", err)
	}
	defer resp.Body.Close()

	respBody, _ := io.ReadAll(resp.Body)
	if resp.StatusCode != http.StatusOK {
		return &ReceiptData{}, fmt.Errorf("Ollama status %d: %s", resp.StatusCode, string(respBody))
	}

	var apiResp ollamaResponse
	json.Unmarshal(respBody, &apiResp)

	if apiResp.Error != "" {
		return &ReceiptData{}, fmt.Errorf("Ollama error: %s", apiResp.Error)
	}

	contentStr := stripMarkdownFences(apiResp.Message.Content)
	var receipt ReceiptData
	if err := json.Unmarshal([]byte(contentStr), &receipt); err != nil {
		return &ReceiptData{}, fmt.Errorf("parse JSON: %w (content: %s)", err, contentStr)
	}

	log.Printf("ExtractReceipt [ollama-%s]: merchant=%q amount=%.2f %s",
		model, receipt.Merchant, receipt.Amount, receipt.Currency)
	return &receipt, nil
}