package ml

import (
	"bytes"
	"crypto/sha256"
	"encoding/hex"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"os"
	"time"
)

// OllamaBaseModelMap maps model tags to Ollama model names.
var OllamaBaseModelMap = map[string]string{
	"gemma-3-1b":  "gemma3:1b",
	"gemma-3-4b":  "gemma3:4b",
	"gemma-3-12b": "gemma3:12b",
	"gemma-3-27b": "gemma3:27b",
}

// HFBaseModelMap maps model tags to HuggingFace model IDs.
var HFBaseModelMap = map[string]string{
	"gemma-3-1b":  "google/gemma-3-1b-it",
	"gemma-3-4b":  "google/gemma-3-4b-it",
	"gemma-3-12b": "google/gemma-3-12b-it",
	"gemma-3-27b": "google/gemma-3-27b-it",
}

// ollamaUploadBlob uploads a local file to Ollama's blob store.
// Returns the sha256 digest string (e.g. "sha256:abc123...").
func ollamaUploadBlob(ollamaURL, filePath string) (string, error) {
	data, err := os.ReadFile(filePath)
	if err != nil {
		return "", fmt.Errorf("read %s: %w", filePath, err)
	}

	hash := sha256.Sum256(data)
	digest := "sha256:" + hex.EncodeToString(hash[:])

	headReq, _ := http.NewRequest(http.MethodHead, ollamaURL+"/api/blobs/"+digest, nil)
	client := &http.Client{Timeout: 5 * time.Minute}
	headResp, err := client.Do(headReq)
	if err == nil && headResp.StatusCode == http.StatusOK {
		headResp.Body.Close()
		return digest, nil
	}
	if headResp != nil {
		headResp.Body.Close()
	}

	req, err := http.NewRequest(http.MethodPost, ollamaURL+"/api/blobs/"+digest, bytes.NewReader(data))
	if err != nil {
		return "", fmt.Errorf("blob request: %w", err)
	}
	req.Header.Set("Content-Type", "application/octet-stream")

	resp, err := client.Do(req)
	if err != nil {
		return "", fmt.Errorf("blob upload: %w", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusCreated && resp.StatusCode != http.StatusOK {
		body, _ := io.ReadAll(resp.Body)
		return "", fmt.Errorf("blob upload HTTP %d: %s", resp.StatusCode, string(body))
	}
	return digest, nil
}

// OllamaCreateModel creates a temporary Ollama model with a LoRA adapter.
// peftDir is a local directory containing adapter_model.safetensors and adapter_config.json.
func OllamaCreateModel(ollamaURL, modelName, baseModel, peftDir string) error {
	sfPath := peftDir + "/adapter_model.safetensors"
	cfgPath := peftDir + "/adapter_config.json"

	sfDigest, err := ollamaUploadBlob(ollamaURL, sfPath)
	if err != nil {
		return fmt.Errorf("upload adapter safetensors: %w", err)
	}

	cfgDigest, err := ollamaUploadBlob(ollamaURL, cfgPath)
	if err != nil {
		return fmt.Errorf("upload adapter config: %w", err)
	}

	reqBody, _ := json.Marshal(map[string]interface{}{
		"model": modelName,
		"from":  baseModel,
		"adapters": map[string]string{
			"adapter_model.safetensors": sfDigest,
			"adapter_config.json":       cfgDigest,
		},
	})

	client := &http.Client{Timeout: 10 * time.Minute}
	resp, err := client.Post(ollamaURL+"/api/create", "application/json", bytes.NewReader(reqBody))
	if err != nil {
		return fmt.Errorf("ollama create: %w", err)
	}
	defer resp.Body.Close()

	decoder := json.NewDecoder(resp.Body)
	for decoder.More() {
		var status struct {
			Status string `json:"status"`
			Error  string `json:"error"`
		}
		if err := decoder.Decode(&status); err != nil {
			if err == io.EOF {
				break
			}
			return fmt.Errorf("ollama create decode: %w", err)
		}
		if status.Error != "" {
			return fmt.Errorf("ollama create: %s", status.Error)
		}
		if status.Status == "success" {
			return nil
		}
	}

	if resp.StatusCode != http.StatusOK {
		return fmt.Errorf("ollama create: HTTP %d", resp.StatusCode)
	}
	return nil
}

// OllamaDeleteModel removes a temporary Ollama model.
func OllamaDeleteModel(ollamaURL, modelName string) error {
	body, _ := json.Marshal(map[string]string{"model": modelName})

	req, err := http.NewRequest(http.MethodDelete, ollamaURL+"/api/delete", bytes.NewReader(body))
	if err != nil {
		return fmt.Errorf("ollama delete request: %w", err)
	}
	req.Header.Set("Content-Type", "application/json")

	client := &http.Client{Timeout: 30 * time.Second}
	resp, err := client.Do(req)
	if err != nil {
		return fmt.Errorf("ollama delete: %w", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		respBody, _ := io.ReadAll(resp.Body)
		return fmt.Errorf("ollama delete %d: %s", resp.StatusCode, string(respBody))
	}
	return nil
}