// Package sonarr provides the small read-only slice of Sonarr used by the home screen.
package sonarr

import (
	"context"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"net/url"
	"strconv"
	"strings"
	"time"
)

type Client struct {
	baseURL string
	apiKey  string
	http    *http.Client
}

type Image struct {
	CoverType string `json:"coverType"`
	URL       string `json:"url"`
	RemoteURL string `json:"remoteUrl"`
}

type Series struct {
	ID       int      `json:"id"`
	Title    string   `json:"title"`
	Overview string   `json:"overview"`
	Year     int      `json:"year"`
	Network  string   `json:"network"`
	Genres   []string `json:"genres"`
	Images   []Image  `json:"images"`
}

type EpisodeFile struct {
	DateAdded *time.Time `json:"dateAdded"`
}

type Episode struct {
	ID            int          `json:"id"`
	SeriesID      int          `json:"seriesId"`
	SeasonNumber  int          `json:"seasonNumber"`
	EpisodeNumber int          `json:"episodeNumber"`
	Title         string       `json:"title"`
	Overview      string       `json:"overview"`
	AirDateUTC    *time.Time   `json:"airDateUtc"`
	Runtime       int          `json:"runtime"`
	HasFile       bool         `json:"hasFile"`
	Monitored     bool         `json:"monitored"`
	Grabbed       bool         `json:"grabbed"`
	Series        Series       `json:"series"`
	EpisodeFile   *EpisodeFile `json:"episodeFile"`
}

type APIError struct {
	StatusCode int
	Body       string
}

func (e *APIError) Error() string {
	return fmt.Sprintf("sonarr: status %d: %s", e.StatusCode, e.Body)
}

func New(baseURL, apiKey string, timeout time.Duration) *Client {
	return &Client{
		baseURL: strings.TrimRight(baseURL, "/"),
		apiKey:  apiKey,
		http: &http.Client{
			Timeout: timeout,
			Transport: &http.Transport{
				MaxIdleConns:        20,
				MaxIdleConnsPerHost: 10,
				IdleConnTimeout:     90 * time.Second,
			},
		},
	}
}

// Calendar returns episodes in [start, end), including series artwork and imported-file
// details so Memby can distinguish upcoming, downloading and already-added episodes.
func (c *Client) Calendar(ctx context.Context, start, end time.Time) ([]Episode, error) {
	params := url.Values{
		"start":                {start.UTC().Format(time.RFC3339Nano)},
		"end":                  {end.UTC().Format(time.RFC3339Nano)},
		"unmonitored":          {"true"},
		"includeSeries":        {"true"},
		"includeEpisodeFile":   {"true"},
		"includeEpisodeImages": {"true"},
	}
	req, err := c.request(ctx, "/api/v3/calendar", params)
	if err != nil {
		return nil, err
	}
	var episodes []Episode
	if err := c.do(req, &episodes); err != nil {
		return nil, err
	}
	return episodes, nil
}

// MediaCover fetches a series poster or fanart without exposing the Sonarr API key.
func (c *Client) MediaCover(ctx context.Context, seriesID int, coverType string) (*http.Response, error) {
	if seriesID <= 0 || (coverType != "poster" && coverType != "fanart") {
		return nil, fmt.Errorf("sonarr: invalid media cover")
	}
	path := "/MediaCover/" + strconv.Itoa(seriesID) + "/" + coverType + ".jpg"
	req, err := c.request(ctx, path, nil)
	if err != nil {
		return nil, err
	}
	req.Header.Set("Accept", "image/*")
	resp, err := c.http.Do(req)
	if err != nil {
		return nil, fmt.Errorf("sonarr: %w", err)
	}
	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
		defer resp.Body.Close()
		body, _ := io.ReadAll(io.LimitReader(resp.Body, 4<<10))
		return nil, &APIError{StatusCode: resp.StatusCode, Body: strings.TrimSpace(string(body))}
	}
	return resp, nil
}

func (c *Client) request(ctx context.Context, path string, params url.Values) (*http.Request, error) {
	endpoint := c.baseURL + path
	if len(params) > 0 {
		endpoint += "?" + params.Encode()
	}
	req, err := http.NewRequestWithContext(ctx, http.MethodGet, endpoint, nil)
	if err != nil {
		return nil, err
	}
	req.Header.Set("X-Api-Key", c.apiKey)
	req.Header.Set("Accept", "application/json")
	return req, nil
}

func (c *Client) do(req *http.Request, out any) error {
	resp, err := c.http.Do(req)
	if err != nil {
		return fmt.Errorf("sonarr: %w", err)
	}
	defer resp.Body.Close()
	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
		body, _ := io.ReadAll(io.LimitReader(resp.Body, 4<<10))
		return &APIError{StatusCode: resp.StatusCode, Body: strings.TrimSpace(string(body))}
	}
	if err := json.NewDecoder(resp.Body).Decode(out); err != nil {
		return fmt.Errorf("sonarr: decode response: %w", err)
	}
	return nil
}