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

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

type Movie struct {
	ID              int        `json:"id"`
	TMDBID          int        `json:"tmdbId"`
	Title           string     `json:"title"`
	TitleSlug       string     `json:"titleSlug"`
	Overview        string     `json:"overview"`
	Year            int        `json:"year"`
	Runtime         int        `json:"runtime"`
	Genres          []string   `json:"genres"`
	Images          []Image    `json:"images"`
	DigitalRelease  *time.Time `json:"digitalRelease"`
	PhysicalRelease *time.Time `json:"physicalRelease"`
	InCinemas       *time.Time `json:"inCinemas"`
	// Radarr's own lifecycle word for the title: tba, announced, inCinemas, released,
	// deleted. It is what the schedule card's lifecycle tag says.
	Status              string     `json:"status"`
	HasFile             bool       `json:"hasFile"`
	Monitored           bool       `json:"monitored"`
	MovieFile           *MovieFile `json:"movieFile"`
	RootFolderPath      string     `json:"rootFolderPath,omitempty"`
	QualityProfileID    int        `json:"qualityProfileId,omitempty"`
	MinimumAvailability string     `json:"minimumAvailability,omitempty"`
}

type RootFolder struct {
	Path string `json:"path"`
}

type QualityProfile struct {
	ID int `json:"id"`
}

type APIError struct {
	StatusCode int
	Body       string
}

func (e *APIError) Error() string {
	return fmt.Sprintf("radarr: 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 movies whose Radarr calendar dates intersect [start, end). Memby
// selects actual digital releases and its cinema-date fallback after fetching the data.
func (c *Client) Calendar(ctx context.Context, start, end time.Time) ([]Movie, error) {
	params := url.Values{
		"start":       {start.UTC().Format(time.RFC3339Nano)},
		"end":         {end.UTC().Format(time.RFC3339Nano)},
		"unmonitored": {"true"},
	}
	req, err := c.request(ctx, "/api/v3/calendar", params)
	if err != nil {
		return nil, err
	}
	var movies []Movie
	if err := c.do(req, &movies); err != nil {
		return nil, err
	}
	return movies, nil
}

func (c *Client) Lookup(ctx context.Context, term string) ([]Movie, error) {
	req, err := c.request(ctx, "/api/v3/movie/lookup", url.Values{"term": {term}})
	if err != nil {
		return nil, err
	}
	var movies []Movie
	if err := c.do(req, &movies); err != nil {
		return nil, err
	}
	return movies, nil
}

// AddRequested adds a title, monitors it and asks Radarr to search for it immediately.
// A request that merely creates an unmonitored catalogue row never reaches a downloader,
// which is indistinguishable from a broken button to the viewer who made it.
func (c *Client) AddRequested(ctx context.Context, movie Movie) (Movie, error) {
	var roots []RootFolder
	if err := c.get(ctx, "/api/v3/rootfolder", &roots); err != nil {
		return Movie{}, err
	}
	var profiles []QualityProfile
	if err := c.get(ctx, "/api/v3/qualityprofile", &profiles); err != nil {
		return Movie{}, err
	}
	if len(roots) == 0 || len(profiles) == 0 {
		return Movie{}, fmt.Errorf("radarr: no root folder or quality profile configured")
	}
	movie.ID = 0
	movie.RootFolderPath = roots[0].Path
	movie.QualityProfileID = profiles[0].ID
	movie.Monitored = true
	body := struct {
		Movie
		AddOptions map[string]bool `json:"addOptions"`
	}{Movie: movie, AddOptions: map[string]bool{"searchForMovie": true}}
	var added Movie
	if err := c.post(ctx, "/api/v3/movie", body, &added); err != nil {
		return Movie{}, err
	}
	return added, nil
}

// MediaCover fetches a movie poster or fanart without exposing the Radarr API key.
func (c *Client) MediaCover(ctx context.Context, movieID int, coverType string) (*http.Response, error) {
	if movieID <= 0 || (coverType != "poster" && coverType != "fanart") {
		return nil, fmt.Errorf("radarr: invalid media cover")
	}
	path := "/MediaCover/" + strconv.Itoa(movieID) + "/" + 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("radarr: %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) get(ctx context.Context, path string, out any) error {
	req, err := c.request(ctx, path, nil)
	if err != nil {
		return err
	}
	return c.do(req, out)
}

func (c *Client) post(ctx context.Context, path string, body, out any) error {
	raw, err := json.Marshal(body)
	if err != nil {
		return fmt.Errorf("radarr: encode request: %w", err)
	}
	req, err := http.NewRequestWithContext(ctx, http.MethodPost, c.baseURL+path, strings.NewReader(string(raw)))
	if err != nil {
		return err
	}
	req.Header.Set("X-Api-Key", c.apiKey)
	req.Header.Set("Accept", "application/json")
	req.Header.Set("Content-Type", "application/json")
	return c.do(req, out)
}

func (c *Client) do(req *http.Request, out any) error {
	resp, err := c.http.Do(req)
	if err != nil {
		return fmt.Errorf("radarr: %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("radarr: decode response: %w", err)
	}
	return nil
}

// Movies returns Radarr's whole catalogue.
//
// The request page needs the current state of every title a viewer has ever asked for, and
// asking Radarr per title would be one round trip per card. One catalogue read answers them
// all; the caller caches it.
func (c *Client) Movies(ctx context.Context) ([]Movie, error) {
	var movies []Movie
	if err := c.get(ctx, "/api/v3/movie", &movies); err != nil {
		return nil, err
	}
	return movies, nil
}