// 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"

	"github.com/ponzischeme89/memby/server/internal/timing"
)

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"`
	// Metadata Radarr carries for a film the household does not hold yet, and which
	// therefore has no Emby record to read it from. It is the whole substance of the
	// Radarr-only detail page; the schedule card itself uses none of it.
	OriginalTitle       string     `json:"originalTitle,omitempty"`
	Studio              string     `json:"studio,omitempty"`
	Certification       string     `json:"certification,omitempty"`
	YouTubeTrailerID    string     `json:"youTubeTrailerId,omitempty"`
	IMDBID              string     `json:"imdbId,omitempty"`
	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"`
}

// SearchMovie asks Radarr to search exactly one tracked film. It does not delete or
// unmonitor the existing file; Radarr retains it until its normal import policy wins.
func (c *Client) SearchMovie(ctx context.Context, movieID int) error {
	if movieID <= 0 {
		return fmt.Errorf("radarr: invalid movie id")
	}
	return c.post(ctx, "/api/v3/command", map[string]any{
		"name": "MoviesSearch", "movieIds": []int{movieID},
	}, &struct{}{})
}

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

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

// RequestOptions are Memby's deliberate movie-request policy. Radarr defaults are never
// allowed to choose a profile or initiate a search on Memby's behalf.
type RequestOptions struct {
	QualityProfileID  int
	SearchImmediately bool
}

func (c *Client) RootFolders(ctx context.Context) ([]RootFolder, error) {
	var roots []RootFolder
	if err := c.get(ctx, "/api/v3/rootfolder", &roots); err != nil {
		return nil, err
	}
	return roots, nil
}

func (c *Client) QualityProfiles(ctx context.Context) ([]QualityProfile, error) {
	var profiles []QualityProfile
	if err := c.get(ctx, "/api/v3/qualityprofile", &profiles); err != nil {
		return nil, err
	}
	return profiles, nil
}

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: timing.Instrument(&http.Client{
			Timeout: timeout,
			Transport: &http.Transport{
				MaxIdleConns:        20,
				MaxIdleConnsPerHost: 10,
				IdleConnTimeout:     90 * time.Second,
			},
		}, timing.StageRadarr),
	}
}

// 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
}

// Movie is one tracked film, for the case the cached catalogue cannot answer: a title
// added to Radarr since the catalogue was last read. The catalogue is still tried first —
// this is the fallback, not the ordinary path, because a detail page opening must not cost
// a round trip Radarr has already answered once for the whole household.
func (c *Client) Movie(ctx context.Context, movieID int) (Movie, error) {
	if movieID <= 0 {
		return Movie{}, fmt.Errorf("radarr: invalid movie id")
	}
	var movie Movie
	if err := c.get(ctx, "/api/v3/movie/"+strconv.Itoa(movieID), &movie); err != nil {
		return Movie{}, err
	}
	return movie, 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 monitored movie using the supplied request policy.
func (c *Client) AddRequested(ctx context.Context, movie Movie, rootFolder string, options RequestOptions) (Movie, error) {
	if strings.TrimSpace(rootFolder) == "" {
		return Movie{}, fmt.Errorf("radarr: request root folder is required")
	}
	if options.QualityProfileID <= 0 {
		return Movie{}, fmt.Errorf("radarr: request quality profile is required")
	}
	movie.ID = 0
	movie.RootFolderPath = rootFolder
	movie.QualityProfileID = options.QualityProfileID
	movie.Monitored = true
	body := struct {
		Movie
		AddOptions map[string]bool `json:"addOptions"`
	}{Movie: movie, AddOptions: map[string]bool{"searchForMovie": options.SearchImmediately}}
	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
}

// QueueItem is one thing the download client is working on, in the narrow shape the
// request page needs: which film, how far through, and how it is going.
//
// Radarr describes a download in three overlapping words rather than one, and all three
// are needed. Status is the *download client's* view (queued, downloading, paused,
// completed, failed, warning, delay). TrackedDownloadState is Radarr's own view of what
// happens after the bytes land (downloading, importPending, importing, imported,
// failedPending, failed) — which is the only thing that separates "still coming down the
// wire" from "almost on the shelf". TrackedDownloadStatus is the verdict (ok, warning,
// error), and is what says an otherwise healthy-looking row has actually gone wrong.
type QueueItem struct {
	ID      int `json:"id"`
	MovieID int `json:"movieId"`
	// Size and Sizeleft are bytes, as floats — Radarr sends them that way, and a film is
	// comfortably past what a 32-bit int holds.
	Size     float64 `json:"size"`
	Sizeleft float64 `json:"sizeleft"`
	// Timeleft is the download client's own estimate, formatted "00:14:32" or
	// "1.02:03:04". It is absent for a queued or stalled item, which is exactly the case
	// where Memby must not invent one.
	Timeleft              string `json:"timeleft"`
	Status                string `json:"status"`
	TrackedDownloadState  string `json:"trackedDownloadState"`
	TrackedDownloadStatus string `json:"trackedDownloadStatus"`
	ErrorMessage          string `json:"errorMessage"`
}

// queuePageSize is what one read asks for. The queue is what the household is downloading
// right now, so it is small by nature; the cap exists so a download client that has wedged
// with a thousand rows cannot turn a request-page refresh into a large response.
const queuePageSize = 200

type queuePage struct {
	Records []QueueItem `json:"records"`
}

// Queue returns what Radarr is currently working on.
//
// Unknown items are excluded: those are downloads in the client that Radarr cannot match
// to a film it tracks, so they can never be the answer to "what is happening to the thing
// I asked for" and would only be rows nothing could use.
func (c *Client) Queue(ctx context.Context) ([]QueueItem, error) {
	req, err := c.request(ctx, "/api/v3/queue", url.Values{
		"pageSize":                 {strconv.Itoa(queuePageSize)},
		"includeUnknownMovieItems": {"false"},
	})
	if err != nil {
		return nil, err
	}
	var page queuePage
	if err := c.do(req, &page); err != nil {
		return nil, err
	}
	return page.Records, nil
}