package daihe

import (
	"bytes"
	"context"
	"crypto/md5"
	"encoding/hex"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"net/url"
	"sort"
	"strings"
	"time"
)

type Config struct {
	BaseURL   string
	AppID     string
	AppSecret string
	Timeout   time.Duration
}

type Client struct {
	baseURL, appID, appSecret string
	httpClient                *http.Client
}

type Response struct {
	Code int             `json:"code"`
	Msg  string          `json:"msg"`
	Data json.RawMessage `json:"data"`
}

func NewClient(cfg Config) *Client {
	timeout := cfg.Timeout
	if timeout <= 0 {
		timeout = 15 * time.Second
	}
	return &Client{baseURL: strings.TrimRight(strings.TrimSpace(cfg.BaseURL), "/"), appID: strings.TrimSpace(cfg.AppID), appSecret: cfg.AppSecret, httpClient: &http.Client{Timeout: timeout}}
}

func BuildSign(params map[string]string, appSecret string) string {
	keys := make([]string, 0, len(params)+1)
	for key := range params {
		if key != "sign" {
			keys = append(keys, key)
		}
	}
	keys = append(keys, "appSecret")
	sort.Strings(keys)
	var b strings.Builder
	for _, key := range keys {
		if key == "appSecret" {
			b.WriteString(key)
			b.WriteString(appSecret)
			continue
		}
		b.WriteString(key)
		b.WriteString(params[key])
	}
	sum := md5.Sum([]byte(b.String()))
	return strings.ToUpper(hex.EncodeToString(sum[:]))
}

func (c *Client) request(ctx context.Context, method, path string, values map[string]string, body any, out any) error {
	if c.baseURL == "" || c.appID == "" || c.appSecret == "" {
		return fmt.Errorf("daihe base URL, appId and appSecret are required")
	}
	params := make(map[string]string, len(values)+1)
	for k, v := range values {
		if strings.TrimSpace(v) != "" {
			params[k] = v
		}
	}
	params["appId"] = c.appID
	params["sign"] = BuildSign(params, c.appSecret)
	var reader io.Reader
	var endpoint string
	if method == http.MethodGet {
		query := url.Values{}
		for k, v := range params {
			query.Set(k, v)
		}
		endpoint = c.baseURL + "/" + strings.TrimLeft(path, "/") + "?" + query.Encode()
	} else {
		payload := map[string]any{}
		if body != nil {
			raw, err := json.Marshal(body)
			if err != nil {
				return fmt.Errorf("marshal daihe request: %w", err)
			}
			if err := json.Unmarshal(raw, &payload); err != nil {
				return fmt.Errorf("marshal daihe request: %w", err)
			}
		}
		for k, v := range params {
			payload[k] = v
		}
		raw, err := json.Marshal(payload)
		if err != nil {
			return fmt.Errorf("marshal daihe request: %w", err)
		}
		reader = bytes.NewReader(raw)
		endpoint = c.baseURL + "/" + strings.TrimLeft(path, "/")
	}
	req, err := http.NewRequestWithContext(ctx, method, endpoint, reader)
	if err != nil {
		return err
	}
	req.Header.Set("Content-Type", "application/json")
	resp, err := c.httpClient.Do(req)
	if err != nil {
		return fmt.Errorf("daihe request failed: %w", err)
	}
	defer resp.Body.Close()
	raw, err := io.ReadAll(io.LimitReader(resp.Body, 4*1024*1024+1))
	if err != nil {
		return err
	}
	if len(raw) > 4*1024*1024 {
		return fmt.Errorf("daihe response is too large")
	}
	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
		return fmt.Errorf("daihe HTTP %d: %s", resp.StatusCode, strings.TrimSpace(string(raw)))
	}
	var envelope Response
	if err := json.Unmarshal(raw, &envelope); err != nil {
		return fmt.Errorf("decode daihe response: %w", err)
	}
	if envelope.Code != 0 {
		return fmt.Errorf("daihe business code %d: %s", envelope.Code, envelope.Msg)
	}
	if out != nil && len(envelope.Data) > 0 && string(envelope.Data) != "null" {
		if err := json.Unmarshal(envelope.Data, out); err != nil {
			return fmt.Errorf("decode daihe data: %w", err)
		}
	}
	return nil
}

type CMCCToken struct {
	AppID       string `json:"appid"`
	Token       string `json:"token"`
	TokenDevice string `json:"token_device"`
	DeviceTTL   string `json:"device_ttl"`
}

func (c *Client) QueryCMCCToken(ctx context.Context, cmccAppID string, out *CMCCToken) error {
	return c.request(ctx, http.MethodGet, "/sim/query/cmccToken", map[string]string{"cmccAppId": cmccAppID}, nil, out)
}

func (c *Client) QueryUsage(ctx context.Context, iccid, month string, out any) error {
	values := map[string]string{"iccid": iccid}
	if month != "" {
		values["month"] = month
	}
	return c.request(ctx, http.MethodGet, "/sim/query/monthUsed", values, nil, out)
}
func (c *Client) QueryStatus(ctx context.Context, iccid string, out any) error {
	return c.request(ctx, http.MethodGet, "/sim/query/status", map[string]string{"iccid": iccid}, nil, out)
}
func (c *Client) Activate(ctx context.Context, iccid string) error {
	return c.request(ctx, http.MethodPost, "/sim/setup/activate", map[string]string{"iccid": iccid}, nil, nil)
}
func (c *Client) Deactivate(ctx context.Context, iccid string) error {
	return c.request(ctx, http.MethodPost, "/sim/setup/deactivate", map[string]string{"iccid": iccid}, nil, nil)
}