package prices

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

const rs3BaseURL = "https://secure.runescape.com/m=itemdb_rs"

// RS3Client wraps HTTP requests to the Jagex RS3 Grand Exchange API.
type RS3Client struct {
	httpClient *http.Client
}

// NewRS3Client creates an RS3 price API client.
func NewRS3Client() *RS3Client {
	return &RS3Client{
		httpClient: &http.Client{
			Timeout: 15 * time.Second,
		},
	}
}

// RS3ItemDetail holds current price and trend data for an RS3 item.
type RS3ItemDetail struct {
	ID           int
	Name         string
	Description  string
	Members      string
	CurrentPrice string // pre-formatted, e.g. "91.6b"
	CurrentTrend string
	TodayPrice   int
	TodayTrend   string
	Day30Change  string
	Day30Trend   string
	Day90Change  string
	Day90Trend   string
	Day180Change string
	Day180Trend  string
}

// rs3DetailResponse matches the JSON shape from the Jagex catalogue API.
type rs3DetailResponse struct {
	Item struct {
		ID          int    `json:"id"`
		Name        string `json:"name"`
		Description string `json:"description"`
		Type        string `json:"type"`
		Members     string `json:"members"`
		Current     struct {
			Trend string      `json:"trend"`
			Price any `json:"price"` // string or int
		} `json:"current"`
		Today struct {
			Trend string `json:"trend"`
			Price any    `json:"price"` // int or string
		} `json:"today"`
		Day30 struct {
			Trend  string `json:"trend"`
			Change string `json:"change"`
		} `json:"day30"`
		Day90 struct {
			Trend  string `json:"trend"`
			Change string `json:"change"`
		} `json:"day90"`
		Day180 struct {
			Trend  string `json:"trend"`
			Change string `json:"change"`
		} `json:"day180"`
	} `json:"item"`
}

// GetDetail fetches current price and trend data for an RS3 item by ID.
func (c *RS3Client) GetDetail(itemID int) (*RS3ItemDetail, error) {
	url := fmt.Sprintf("%s/api/catalogue/detail.json?item=%d", rs3BaseURL, itemID)

	req, err := http.NewRequest("GET", url, nil)
	if err != nil {
		return nil, fmt.Errorf("creating request: %w", err)
	}
	req.Header.Set("User-Agent", userAgent)

	resp, err := c.httpClient.Do(req)
	if err != nil {
		return nil, fmt.Errorf("executing request: %w", err)
	}
	defer resp.Body.Close() //nolint:errcheck

	if resp.StatusCode != http.StatusOK {
		body, _ := io.ReadAll(resp.Body)
		return nil, fmt.Errorf("RS3 API returned status %d: %s", resp.StatusCode, string(body))
	}

	var raw rs3DetailResponse
	if err := json.NewDecoder(resp.Body).Decode(&raw); err != nil {
		return nil, fmt.Errorf("decoding response: %w", err)
	}

	detail := &RS3ItemDetail{
		ID:           raw.Item.ID,
		Name:         raw.Item.Name,
		Description:  raw.Item.Description,
		Members:      raw.Item.Members,
		CurrentPrice: fmt.Sprintf("%v", raw.Item.Current.Price),
		CurrentTrend: raw.Item.Current.Trend,
		TodayTrend:   raw.Item.Today.Trend,
		Day30Change:  raw.Item.Day30.Change,
		Day30Trend:   raw.Item.Day30.Trend,
		Day90Change:  raw.Item.Day90.Change,
		Day90Trend:   raw.Item.Day90.Trend,
		Day180Change: raw.Item.Day180.Change,
		Day180Trend:  raw.Item.Day180.Trend,
	}

	// today.price can be int or string
	switch v := raw.Item.Today.Price.(type) {
	case float64:
		detail.TodayPrice = int(v)
	}

	return detail, nil
}