package upstreamimpl

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

	sharedtoken "git.5iot.com/iotlcm-public/iotlcm-upstream-chan/internal/token"
)

// LanShangTokenConfig contains the endpoint from the template and credentials
// from the channel configuration.
type LanShangTokenConfig struct {
	BaseURL    string
	Path       string
	SubAccount string
	Secret     string
	Timeout    time.Duration
}

type LanShangTokenProvider struct {
	baseURL    string
	path       string
	subAccount string
	secret     string
	client     *http.Client
}

type lanShangTokenResponse struct {
	Token    string `json:"token"`
	ExpireIn int    `json:"expire_in"`
}

type lanshangFetcher struct{ provider *LanShangTokenProvider }

func NewLanShangTokenProvider(config LanShangTokenConfig) *LanShangTokenProvider {
	timeout := config.Timeout
	if timeout <= 0 {
		timeout = defaultUpstreamHTTPTimeout
	}
	return &LanShangTokenProvider{
		baseURL:    strings.TrimRight(strings.TrimSpace(config.BaseURL), "/"),
		path:       normalizeProviderPath(config.Path, "/get_token"),
		subAccount: strings.TrimSpace(config.SubAccount),
		secret:     config.Secret,
		client:     &http.Client{Timeout: timeout},
	}
}

func (f lanshangFetcher) FetchToken(ctx context.Context, _ string) (sharedtoken.OneLinkToken, error) {
	return f.provider.Fetch(ctx)
}

func (p *LanShangTokenProvider) Fetch(ctx context.Context) (sharedtoken.OneLinkToken, error) {
	if p == nil || p.client == nil {
		return sharedtoken.OneLinkToken{}, fmt.Errorf("lanshang token provider is not initialized")
	}
	if p.baseURL == "" || p.subAccount == "" || p.secret == "" {
		return sharedtoken.OneLinkToken{}, fmt.Errorf("lanshang token endpoint and credentials are required")
	}

	endpoint, err := url.Parse(joinProviderURL(p.baseURL, p.path))
	if err != nil {
		return sharedtoken.OneLinkToken{}, fmt.Errorf("parse lanshang token URL: %w", err)
	}
	query := endpoint.Query()
	query.Set("sub_account", p.subAccount)
	query.Set("secret", p.secret)
	endpoint.RawQuery = query.Encode()

	req, err := http.NewRequestWithContext(ctx, http.MethodGet, endpoint.String(), nil)
	if err != nil {
		return sharedtoken.OneLinkToken{}, fmt.Errorf("create lanshang token request: %w", err)
	}
	req.Header.Set("Accept", "application/json")
	resp, err := p.client.Do(req)
	if err != nil {
		return sharedtoken.OneLinkToken{}, fmt.Errorf("request lanshang token: %w", err)
	}
	defer resp.Body.Close()
	body, err := io.ReadAll(resp.Body)
	if err != nil {
		return sharedtoken.OneLinkToken{}, fmt.Errorf("read lanshang token response: %w", err)
	}
	if resp.StatusCode < http.StatusOK || resp.StatusCode >= http.StatusMultipleChoices {
		return sharedtoken.OneLinkToken{}, fmt.Errorf("lanshang token HTTP status %d", resp.StatusCode)
	}

	var output lanShangTokenResponse
	if err := json.Unmarshal(body, &output); err != nil {
		return sharedtoken.OneLinkToken{}, fmt.Errorf("decode lanshang token response: %w", err)
	}
	value := strings.TrimSpace(output.Token)
	if value == "" {
		return sharedtoken.OneLinkToken{}, fmt.Errorf("lanshang token is empty")
	}
	now := time.Now()
	expiresAt := time.Time{}
	if output.ExpireIn > 0 {
		expiresAt = now.Add(time.Duration(output.ExpireIn) * time.Second)
	}
	return sharedtoken.OneLinkToken{Value: value, CreatedAt: now, ExpiresAt: expiresAt}, nil
}

func (p *LanShangTokenProvider) FetchToken(ctx context.Context, _ string) (sharedtoken.OneLinkToken, error) {
	return p.Fetch(ctx)
}