package ntfy

import (
	"context"
	"fmt"
	"io"
	"net"
	"net/http"
	"strconv"
	"strings"
	"time"

	"lazyntfy/internal/config"
)

const userAgent = "lazyntfy/0.1.0"

// Client talks to an ntfy server over HTTP.
type Client struct {
	HTTP *http.Client
}

// NewClient returns a client whose timeout covers the handshake, not the
// long-lived response body.
func NewClient() *Client {
	return &Client{HTTP: &http.Client{Transport: &http.Transport{
		Proxy: http.ProxyFromEnvironment,
		DialContext: (&net.Dialer{
			Timeout:   10 * time.Second,
			KeepAlive: 30 * time.Second,
		}).DialContext,
		TLSHandshakeTimeout:   10 * time.Second,
		ResponseHeaderTimeout: 30 * time.Second,
		IdleConnTimeout:       90 * time.Second,
		ExpectContinueTimeout: 1 * time.Second,
	}}}
}

func (c *Client) http() *http.Client {
	if c != nil && c.HTTP != nil {
		return c.HTTP
	}
	return http.DefaultClient
}

// PublishRequest is a plain-text ntfy publish.
type PublishRequest struct {
	Title    string
	Message  string
	Priority int
	Tags     []string
}

// StreamMeta is returned once response headers have been read.
type StreamMeta struct {
	Truncated bool
}

// OpenStream starts a JSON subscription. The caller must close the body.
func (c *Client) OpenStream(ctx context.Context, endpoint string, auth config.Auth) (*http.Response, StreamMeta, error) {
	req, err := http.NewRequestWithContext(ctx, http.MethodGet, endpoint, nil)
	if err != nil {
		return nil, StreamMeta{}, err
	}
	req.Header.Set("User-Agent", userAgent)
	req.Header.Set("Accept", "application/x-ndjson")
	auth.Apply(req)
	resp, err := c.http().Do(req)
	if err != nil {
		return nil, StreamMeta{}, err
	}
	if resp.StatusCode != http.StatusOK {
		defer resp.Body.Close()
		return nil, StreamMeta{}, httpStatusError(resp)
	}
	return resp, StreamMeta{Truncated: resp.Header.Get("X-Messages-Truncated") == "1"}, nil
}

// Publish sends a message to one topic.
func (c *Client) Publish(ctx context.Context, origin, name string, auth config.Auth, msg PublishRequest) error {
	if strings.TrimSpace(msg.Message) == "" {
		return fmt.Errorf("message is empty")
	}
	req, err := http.NewRequestWithContext(ctx, http.MethodPost, PublishURL(origin, name), strings.NewReader(msg.Message))
	if err != nil {
		return err
	}
	req.Header.Set("User-Agent", userAgent)
	req.Header.Set("Content-Type", "text/plain; charset=utf-8")
	if msg.Title != "" {
		req.Header.Set("Title", msg.Title)
	}
	if msg.Priority > 0 {
		req.Header.Set("Priority", priorityHeader(msg.Priority))
	}
	if len(msg.Tags) > 0 {
		req.Header.Set("Tags", strings.Join(msg.Tags, ","))
	}
	auth.Apply(req)
	resp, err := c.http().Do(req)
	if err != nil {
		return err
	}
	defer resp.Body.Close()
	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
		return httpStatusError(resp)
	}
	_, _ = io.Copy(io.Discard, io.LimitReader(resp.Body, 4096))
	return nil
}

func httpStatusError(resp *http.Response) error {
	if resp.StatusCode == http.StatusUnauthorized || resp.StatusCode == http.StatusForbidden {
		return fmt.Errorf("HTTP %d: not authorized for this topic", resp.StatusCode)
	}
	body, _ := io.ReadAll(io.LimitReader(resp.Body, 512))
	msg := strings.TrimSpace(string(body))
	msg = strings.ReplaceAll(msg, "\n", " ")
	if msg == "" {
		return fmt.Errorf("HTTP %s", resp.Status)
	}
	return fmt.Errorf("HTTP %s: %s", resp.Status, msg)
}

func priorityHeader(p int) string {
	switch p {
	case 1:
		return "min"
	case 2:
		return "low"
	case 3:
		return "default"
	case 4:
		return "high"
	case 5:
		return "max"
	default:
		return strconv.Itoa(p)
	}
}

// ParsePriority accepts 1-5 or the ntfy names min, low, default, high, and max.
func ParsePriority(s string) (int, error) {
	s = strings.ToLower(strings.TrimSpace(s))
	if s == "" {
		return 3, nil
	}
	switch s {
	case "min", "1":
		return 1, nil
	case "low", "2":
		return 2, nil
	case "default", "def", "3":
		return 3, nil
	case "high", "4":
		return 4, nil
	case "max", "urgent", "5":
		return 5, nil
	default:
		return 0, fmt.Errorf("priority must be 1-5 or min/low/default/high/max")
	}
}

// ParseTags splits a comma-separated tag list.
func ParseTags(s string) []string {
	if strings.TrimSpace(s) == "" {
		return nil
	}
	parts := strings.Split(s, ",")
	out := make([]string, 0, len(parts))
	for _, p := range parts {
		p = strings.TrimSpace(p)
		if p != "" {
			out = append(out, p)
		}
	}
	return out
}