package upstreamimpl

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

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

// HenanXinjingTokenConfig carries the credentials needed to call the
// platform's `/api/v1/searchToken` endpoint and convert the response into a
// sharedtoken.OneLinkToken for the sharedtoken manager.
//
// The channel card-no is optional at construction time because the
// underlying platform scopes tokens to (channel_id, channel_pname), not to
// a specific card. When CardNo is empty the fetcher falls back to the
// chanKey passed by the token manager (matching how zibo/tengyu providers
// treat the per-channel seed value).
type HenanXinjingTokenConfig struct {
	BaseURL      string
	Path         string // defaults to /api/v1/searchToken
	UserID       string
	APIKey       string
	ChannelID    string // e.g. "80", "97", "194"
	ChannelPName string // e.g. "cmiotonelinkqx"
	CardNo       string // optional seed card number; may be overridden by manager
	Timeout      time.Duration
}

// HenanXinjingTokenProvider fetches a shared token for a given
// (userId, channel_id, channel_pname) triple from the Henan Xinjing
// platform.
type HenanXinjingTokenProvider struct {
	baseURL, path, userID, apiKey, channelID, channelPName, cardNo string
	client                                                         *http.Client
}

// henanXinjingSearchTokenResponse matches the upstream response shape:
//
//	{
//	  "code": 0,
//	  "msg": "查询成功",
//	  "data": {
//	    "id": 80,
//	    "chl_username": "C5010371A16640006582238",
//	    "accesstoken": "v1b74e73d741cea620f0ceecaf7a733fa6964aa53fffcbf8d3a5a4c8715aabe3",
//	    "accesstoken_at": "2026-09-16 13:19:29"
//	  }
//	}
//
// `code` may be either a JSON number or string; decode via henanXinjingDecodeCode.
type henanXinjingSearchTokenResponse struct {
	Code json.RawMessage `json:"code"`
	Msg  string          `json:"msg"`
	Data struct {
		ID               json.RawMessage `json:"id"`
		ChlUsername      string          `json:"chl_username"`
		AccessToken      string          `json:"accesstoken"`
		AccessTokenAt    string          `json:"accesstoken_at"`
		AccessTokenSB    string          `json:"accesstokensb"`
		AccessTokenAlias string          `json:"access_token"`
	} `json:"data"`
}

const (
	henanXinjingSearchTokenPath     = "/api/v1/searchToken"
	henanXinjingTokenExpiryLayout   = "2006-01-02 15:04:05"
	henanXinjingTokenRefreshBackoff = 5 * time.Minute
)

func NewHenanXinjingTokenProvider(config HenanXinjingTokenConfig) *HenanXinjingTokenProvider {
	timeout := config.Timeout
	if timeout <= 0 {
		timeout = defaultUpstreamHTTPTimeout
	}
	return &HenanXinjingTokenProvider{
		baseURL:      strings.TrimRight(strings.TrimSpace(config.BaseURL), "/"),
		path:         normalizeProviderPath(config.Path, henanXinjingSearchTokenPath),
		userID:       strings.TrimSpace(config.UserID),
		apiKey:       strings.TrimSpace(config.APIKey),
		channelID:    strings.TrimSpace(config.ChannelID),
		channelPName: strings.TrimSpace(config.ChannelPName),
		cardNo:       strings.TrimSpace(config.CardNo),
		client:       &http.Client{Timeout: timeout},
	}
}

// parseExpiry interprets the platform's `accesstoken_at` field. The
// platform uses local China time without an explicit zone, so parse in
// Asia/Shanghai.
func henanXinjingParseExpiry(raw string) (time.Time, error) {
	raw = strings.TrimSpace(raw)
	if raw == "" {
		return time.Time{}, fmt.Errorf("empty accesstoken_at")
	}
	loc, err := time.LoadLocation("Asia/Shanghai")
	if err != nil {
		loc = time.Local
	}
	t, err := time.ParseInLocation(henanXinjingTokenExpiryLayout, raw, loc)
	if err != nil {
		return time.Time{}, fmt.Errorf("parse accesstoken_at %q: %w", raw, err)
	}
	return t, nil
}

// firstToken returns the first non-empty token field. The platform has been
// observed returning the token under `accesstoken`, but earlier docs
// referenced `accesstokensb` / `access_token`; accept all three.
func henanXinjingFirstToken(resp *henanXinjingSearchTokenResponse) string {
	if v := strings.TrimSpace(resp.Data.AccessToken); v != "" {
		return v
	}
	if v := strings.TrimSpace(resp.Data.AccessTokenSB); v != "" {
		return v
	}
	return strings.TrimSpace(resp.Data.AccessTokenAlias)
}

// fetch performs the signed GET against /api/v1/searchToken for the given
// card number. Card number may come from the manager's chanKey seed.
func (p *HenanXinjingTokenProvider) fetch(ctx context.Context, cardNo string) (sharedtoken.OneLinkToken, error) {
	if p == nil || p.client == nil {
		return sharedtoken.OneLinkToken{}, fmt.Errorf("henan xinjing token provider is not initialized")
	}
	if p.baseURL == "" || p.userID == "" || p.apiKey == "" || p.channelID == "" || p.channelPName == "" {
		return sharedtoken.OneLinkToken{}, fmt.Errorf("henan xinjing: baseURL, userID, apiKey, channelID and channelPName are required")
	}
	cardNo = strings.TrimSpace(cardNo)
	if cardNo == "" {
		cardNo = p.cardNo
	}
	// cardno is optional on the real platform (verified live): the token is
	// scoped to (userId, channel_id, channel_pname), so omit the param when
	// no seed card number is configured instead of failing the fetch.

	times := strconv.FormatInt(time.Now().Unix(), 10)
	values := url.Values{}
	values.Set("userId", p.userID)
	if cardNo != "" {
		values.Set("cardno", cardNo)
	}
	values.Set("channel_id", p.channelID)
	values.Set("channel_pname", p.channelPName)
	values.Set("times", times)
	values.Set("sign", henanXinjingSign(p.userID, p.apiKey, times))

	endpoint := p.baseURL + p.path + "?" + values.Encode()
	req, err := http.NewRequestWithContext(ctx, http.MethodGet, endpoint, nil)
	if err != nil {
		return sharedtoken.OneLinkToken{}, fmt.Errorf("henan xinjing: build searchToken request: %w", err)
	}
	resp, err := p.client.Do(req)
	if err != nil {
		return sharedtoken.OneLinkToken{}, fmt.Errorf("henan xinjing: request searchToken: %w", err)
	}
	defer resp.Body.Close()
	body, err := io.ReadAll(resp.Body)
	if err != nil {
		return sharedtoken.OneLinkToken{}, fmt.Errorf("henan xinjing: read searchToken body: %w", err)
	}
	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
		return sharedtoken.OneLinkToken{}, fmt.Errorf("henan xinjing: searchToken HTTP %d: %s", resp.StatusCode, string(body))
	}
	var output henanXinjingSearchTokenResponse
	if err := json.Unmarshal(body, &output); err != nil {
		return sharedtoken.OneLinkToken{}, fmt.Errorf("henan xinjing: decode searchToken response: %w (body=%s)", err, string(body))
	}
	code, err := henanXinjingDecodeCode(output.Code)
	if err != nil {
		return sharedtoken.OneLinkToken{}, fmt.Errorf("henan xinjing: searchToken: %w (body=%s)", err, string(body))
	}
	if code != 0 {
		return sharedtoken.OneLinkToken{}, fmt.Errorf("henan xinjing: searchToken failed: code=%d msg=%s", code, output.Msg)
	}
	tokenValue := henanXinjingFirstToken(&output)
	if tokenValue == "" {
		return sharedtoken.OneLinkToken{}, fmt.Errorf("henan xinjing: searchToken returned empty accesstoken")
	}
	expiresAt, err := henanXinjingParseExpiry(output.Data.AccessTokenAt)
	if err != nil {
		return sharedtoken.OneLinkToken{}, err
	}
	// Refresh slightly ahead of the declared expiry to absorb clock skew.
	if until := time.Until(expiresAt); until > henanXinjingTokenRefreshBackoff {
		expiresAt = expiresAt.Add(-henanXinjingTokenRefreshBackoff)
	}
	return sharedtoken.OneLinkToken{
		Value:     tokenValue,
		CreatedAt: time.Now(),
		ExpiresAt: expiresAt,
	}, nil
}

// Fetch satisfies the sharedtoken.Fetcher-style interface used by the
// token manager. The chanKey argument is unused here because Henan Xinjing
// scopes tokens to the (channel_id, channel_pname) pair rather than to a
// specific chan_key; we always fetch with the configured cardNo.
func (p *HenanXinjingTokenProvider) Fetch(ctx context.Context) (sharedtoken.OneLinkToken, error) {
	return p.fetch(ctx, "")
}

// FetchToken matches the sharedtoken.TokenFetcher interface used by
// sharedtoken.NewTokenManager. chanKey is the token manager's cache key
// (typically the channel's chan_key); it does not influence the upstream
// request but lets the manager cache one token per channel.
func (p *HenanXinjingTokenProvider) FetchToken(ctx context.Context, _ string) (sharedtoken.OneLinkToken, error) {
	return p.fetch(ctx, "")
}

// henanXinjingFetcher adapts HenanXinjingTokenProvider to the sharedtoken
// fetcher shape used by RegisterTokenProviderFactory.
type henanXinjingFetcher struct{ provider *HenanXinjingTokenProvider }

func (f henanXinjingFetcher) FetchToken(ctx context.Context, chanKey string) (sharedtoken.OneLinkToken, error) {
	return f.provider.fetch(ctx, "")
}