// Package arr provides clients for Radarr, Sonarr, and Lidarr.
//
// Each client exposes Search to look up candidates by free-text query and
// Add to enqueue the first/chosen candidate for download. Lookup responses
// are preserved as raw JSON inside Result so Add can replay the entity back
// to the *arr server with the configured profile and root folder layered on.
package arr

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

// Result is a single candidate returned by an *arr lookup. Title and Year
// are extracted for display; raw is the untouched JSON object used to build
// the Add payload.
type Result struct {
	Title string
	Year  int
	raw   json.RawMessage
}

// Raw exposes the underlying lookup JSON; useful for tests and debugging.
func (r Result) Raw() json.RawMessage { return r.raw }

// Client is the common interface implemented by every *arr backend.
type Client interface {
	Search(ctx context.Context, term string) ([]Result, error)
	Add(ctx context.Context, r Result) error
}

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

func newHTTP(baseURL, apiKey string) *httpClient {
	return &httpClient{
		baseURL: strings.TrimRight(baseURL, "/"),
		apiKey:  apiKey,
		hc:      &http.Client{Timeout: 30 * time.Second},
	}
}

func (c *httpClient) get(ctx context.Context, path string, query map[string]string) ([]byte, error) {
	req, err := http.NewRequestWithContext(ctx, http.MethodGet, c.baseURL+path, nil)
	if err != nil {
		return nil, err
	}
	if len(query) > 0 {
		q := req.URL.Query()
		for k, v := range query {
			q.Set(k, v)
		}
		req.URL.RawQuery = q.Encode()
	}
	return c.do(req)
}

func (c *httpClient) post(ctx context.Context, path string, body []byte) ([]byte, error) {
	req, err := http.NewRequestWithContext(ctx, http.MethodPost, c.baseURL+path, bytes.NewReader(body))
	if err != nil {
		return nil, err
	}
	req.Header.Set("Content-Type", "application/json")
	return c.do(req)
}

func (c *httpClient) do(req *http.Request) ([]byte, error) {
	req.Header.Set("X-Api-Key", c.apiKey)
	req.Header.Set("Accept", "application/json")
	resp, err := c.hc.Do(req)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()
	body, err := io.ReadAll(resp.Body)
	if err != nil {
		return nil, fmt.Errorf("read response: %w", err)
	}
	if resp.StatusCode >= 400 {
		return nil, fmt.Errorf("%s %s: %d: %s", req.Method, req.URL.Path, resp.StatusCode, strings.TrimSpace(string(body)))
	}
	return body, nil
}

// parseLookup decodes a lookup response into Results, pulling Title/Year out
// of each item while keeping the original JSON object intact.
func parseLookup(body []byte, titleField string) ([]Result, error) {
	var items []json.RawMessage
	if err := json.Unmarshal(body, &items); err != nil {
		return nil, fmt.Errorf("decode lookup: %w", err)
	}
	out := make([]Result, 0, len(items))
	for _, item := range items {
		var meta map[string]json.RawMessage
		if err := json.Unmarshal(item, &meta); err != nil {
			continue
		}
		var title string
		_ = json.Unmarshal(meta[titleField], &title)
		var year int
		_ = json.Unmarshal(meta["year"], &year)
		out = append(out, Result{Title: title, Year: year, raw: item})
	}
	return out, nil
}

// buildAddBody decodes the raw lookup item into a generic map, overlays the
// provided fields, and re-marshals. Each *arr backend supplies the fields
// specific to its add endpoint.
func buildAddBody(raw json.RawMessage, overlay map[string]any) ([]byte, error) {
	var m map[string]any
	if err := json.Unmarshal(raw, &m); err != nil {
		return nil, fmt.Errorf("decode lookup item: %w", err)
	}
	for k, v := range overlay {
		m[k] = v
	}
	return json.Marshal(m)
}