package server

import (
	"fmt"
	"os"
	"path"
	"path/filepath"
	"strconv"

	"github.com/jmorganca/ollama/api"
)

type Model struct {
	Name             string `json:"name"`
	ModelPath        string
	Prompt           string
	Options          api.Options
	DisplayName      string `json:"display_name"`
	Parameters       string `json:"parameters"`
	URL              string `json:"url"`
	ShortDescription string `json:"short_description"`
	Description      string `json:"description"`
	PublishedBy      string `json:"published_by"`
	OriginalAuthor   string `json:"original_author"`
	OriginalURL      string `json:"original_url"`
	License          string `json:"license"`
}

func saveModel(model *Model, fn func(total, completed int64)) error {
	// this models cache directory is created by the server on startup

	client := &http.Client{}
	req, err := http.NewRequest("GET", model.URL, nil)
	if err != nil {
		return fmt.Errorf("failed to download model: %w", err)
	}

	var size int64

	// completed file doesn't exist, check partial file
	fi, err := os.Stat(model.TempFile())
	switch {
	case errors.Is(err, os.ErrNotExist):
		// noop, file doesn't exist so create it
	case err != nil:
		return fmt.Errorf("stat: %w", err)
	default:
		size = fi.Size()
	}

	req.Header.Add("Range", fmt.Sprintf("bytes=%d-", size))

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

	if resp.StatusCode >= 400 {
		return fmt.Errorf("failed to download model: %s", resp.Status)
	}

	out, err := os.OpenFile(model.TempFile(), os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0o644)
	if err != nil {
		panic(err)
	}
	defer out.Close()

	remaining, _ := strconv.ParseInt(resp.Header.Get("Content-Length"), 10, 64)
	completed := size

	total := remaining + completed

	for {
		fn(total, completed)
		if completed >= total {
			return os.Rename(model.TempFile(), model.FullName())
		}

		n, err := io.CopyN(out, resp.Body, 8192)
		if err != nil && !errors.Is(err, io.EOF) {
			return err
		}

		completed += n
	}
}