package prices

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

const userAgent = "rsw-cli/1.0 (RuneScape Wiki CLI tool; https://github.com/runescape-wiki/rsw)"

// Client wraps HTTP requests to the real-time prices API.
type Client struct {
	baseURL    string
	httpClient *http.Client
}

// NewClient creates a price API client.
func NewClient(baseURL string) *Client {
	return &Client{
		baseURL: baseURL,
		httpClient: &http.Client{
			Timeout: 15 * time.Second,
		},
	}
}

// LatestPrice represents the current GE price for an item.
type LatestPrice struct {
	High     *int   `json:"high"`
	HighTime *int64 `json:"highTime"`
	Low      *int   `json:"low"`
	LowTime  *int64 `json:"lowTime"`
}

// LatestResponse maps item IDs to their latest prices.
type LatestResponse struct {
	Data map[string]LatestPrice `json:"data"`
}

// MappingItem maps an item ID to metadata.
type MappingItem struct {
	ID       int    `json:"id"`
	Name     string `json:"name"`
	Examine  string `json:"examine"`
	Members  bool   `json:"members"`
	HighAlch *int   `json:"highalch"`
	LowAlch  *int   `json:"lowalch"`
	Limit    *int   `json:"limit"`
	Value    int    `json:"value"`
	Icon     string `json:"icon"`
}

// GetLatest fetches the latest prices for all items.
func (c *Client) GetLatest() (*LatestResponse, error) {
	url := fmt.Sprintf("%s/latest", c.baseURL)
	var resp LatestResponse
	if err := c.getJSON(url, &resp); err != nil {
		return nil, err
	}
	return &resp, nil
}

// GetLatestForItem fetches the latest price for a specific item by ID.
func (c *Client) GetLatestForItem(itemID int) (*LatestPrice, error) {
	url := fmt.Sprintf("%s/latest?id=%d", c.baseURL, itemID)
	var resp LatestResponse
	if err := c.getJSON(url, &resp); err != nil {
		return nil, err
	}
	idStr := fmt.Sprintf("%d", itemID)
	if p, ok := resp.Data[idStr]; ok {
		return &p, nil
	}
	return nil, fmt.Errorf("no price data for item %d", itemID)
}

// GetMapping fetches the item ID → metadata mapping.
func (c *Client) GetMapping() ([]MappingItem, error) {
	url := fmt.Sprintf("%s/mapping", c.baseURL)
	var resp []MappingItem
	if err := c.getJSON(url, &resp); err != nil {
		return nil, err
	}
	return resp, nil
}

// VolumeEntry represents trade volume data for an item.
type VolumeEntry struct {
	AvgHighPrice *int  `json:"avgHighPrice"`
	HighVolume   int   `json:"highPriceVolume"`
	AvgLowPrice  *int  `json:"avgLowPrice"`
	LowVolume    int   `json:"lowPriceVolume"`
	Timestamp    int64 `json:"timestamp"`
}

// TimeseriesResponse wraps the 5m/1h API responses.
// The API returns data as a map keyed by item ID string.
type TimeseriesResponse struct {
	Data map[string]VolumeEntry `json:"data"`
}

// Get5Min fetches 5-minute average data for an item.
func (c *Client) Get5Min(itemID int) (*VolumeEntry, error) {
	url := fmt.Sprintf("%s/5m?id=%d", c.baseURL, itemID)
	var resp TimeseriesResponse
	if err := c.getJSON(url, &resp); err != nil {
		return nil, err
	}
	idStr := fmt.Sprintf("%d", itemID)
	if entry, ok := resp.Data[idStr]; ok {
		return &entry, nil
	}
	return nil, fmt.Errorf("no 5m data for item %d", itemID)
}

// Get1Hour fetches 1-hour average data for an item.
func (c *Client) Get1Hour(itemID int) (*VolumeEntry, error) {
	url := fmt.Sprintf("%s/1h?id=%d", c.baseURL, itemID)
	var resp TimeseriesResponse
	if err := c.getJSON(url, &resp); err != nil {
		return nil, err
	}
	idStr := fmt.Sprintf("%d", itemID)
	if entry, ok := resp.Data[idStr]; ok {
		return &entry, nil
	}
	return nil, fmt.Errorf("no 1h data for item %d", itemID)
}

func (c *Client) getJSON(url string, dest any) error {
	req, err := http.NewRequest("GET", url, nil)
	if err != nil {
		return fmt.Errorf("creating request: %w", err)
	}
	req.Header.Set("User-Agent", userAgent)

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

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

	return json.NewDecoder(resp.Body).Decode(dest)
}