package httpapi

import (
	"database/sql"
	"encoding/json"
	"net/http"
	"time"

	"github.com/wangjia/pangolin/server/internal/apierr"
	"github.com/wangjia/pangolin/server/internal/auth"
)

// AccountAPI serves /v1/me and supporting endpoints.
type AccountAPI struct {
	db *sql.DB
}

// NewAccountAPI creates an AccountAPI.
func NewAccountAPI(db *sql.DB) *AccountAPI { return &AccountAPI{db: db} }

// ─── GET /v1/me ──────────────────────────────────────────────────────────────

type meResponse struct {
	UUID     string      `json:"uuid"`
	Email    string      `json:"email"`
	DpUUID   string      `json:"dp_uuid"`
	Plan     string      `json:"plan"`      // "free" | "pro" | "team"
	ExpireAt *string     `json:"expire_at"` // RFC3339 UTC, null = no active sub
}

// GetMe handles GET /v1/me.
func (a *AccountAPI) GetMe(w http.ResponseWriter, r *http.Request) {
	uid, ok := auth.UserIDFromContext(r.Context())
	if !ok {
		apierr.WriteJSON(w, http.StatusUnauthorized, apierr.ErrUnauthorized)
		return
	}

	var (
		uuid   string
		email  string
		dpUUID string
	)
	if err := a.db.QueryRowContext(r.Context(),
		`SELECT uuid, email, dp_uuid FROM users WHERE id = ? AND status = 'active'`, uid,
	).Scan(&uuid, &email, &dpUUID); err == sql.ErrNoRows {
		apierr.WriteJSON(w, http.StatusNotFound, apierr.ErrNotFound)
		return
	} else if err != nil {
		apierr.WriteJSON(w, http.StatusInternalServerError, apierr.ErrInternal)
		return
	}

	// Best active subscription.
	var planCode string
	var expiresAt sql.NullTime
	err := a.db.QueryRowContext(r.Context(), `
		SELECT p.code, s.expires_at
		FROM subscriptions s
		JOIN plans p ON p.id = s.plan_id
		WHERE s.user_id = ? AND s.expires_at > UTC_TIMESTAMP()
		ORDER BY s.expires_at DESC
		LIMIT 1
	`, uid).Scan(&planCode, &expiresAt)
	if err == sql.ErrNoRows {
		planCode = "free"
	} else if err != nil {
		apierr.WriteJSON(w, http.StatusInternalServerError, apierr.ErrInternal)
		return
	}

	resp := meResponse{
		UUID:   uuid,
		Email:  email,
		DpUUID: dpUUID,
		Plan:   planCode,
	}
	if expiresAt.Valid {
		s := expiresAt.Time.UTC().Format(time.RFC3339)
		resp.ExpireAt = &s
	}

	w.Header().Set("Content-Type", "application/json; charset=utf-8")
	_ = json.NewEncoder(w).Encode(resp)
}

// ─── GET /v1/plans ───────────────────────────────────────────────────────────

type planResponse struct {
	Code         string  `json:"code"`
	NameZH       string  `json:"name_zh"`
	NameEN       string  `json:"name_en"`
	DailyMinutes *int64  `json:"daily_minutes"` // null = unlimited
	AdGate       bool    `json:"ad_gate"`
}

// ListPlans handles GET /v1/plans.
func (a *AccountAPI) ListPlans(w http.ResponseWriter, r *http.Request) {
	rows, err := a.db.QueryContext(r.Context(),
		`SELECT code, name_zh, name_en, daily_minutes, ad_gate FROM plans ORDER BY id`)
	if err != nil {
		apierr.WriteJSON(w, http.StatusInternalServerError, apierr.ErrInternal)
		return
	}
	defer rows.Close()

	var plans []planResponse
	for rows.Next() {
		var p planResponse
		var dm sql.NullInt64
		if err := rows.Scan(&p.Code, &p.NameZH, &p.NameEN, &dm, &p.AdGate); err != nil {
			apierr.WriteJSON(w, http.StatusInternalServerError, apierr.ErrInternal)
			return
		}
		if dm.Valid {
			p.DailyMinutes = &dm.Int64
		}
		plans = append(plans, p)
	}
	if err := rows.Err(); err != nil {
		apierr.WriteJSON(w, http.StatusInternalServerError, apierr.ErrInternal)
		return
	}

	w.Header().Set("Content-Type", "application/json; charset=utf-8")
	_ = json.NewEncoder(w).Encode(map[string]any{"plans": plans})
}

// ─── GET /v1/notices ─────────────────────────────────────────────────────────

// ListNotices handles GET /v1/notices. Returns an empty list for the MVP.
func (a *AccountAPI) ListNotices(w http.ResponseWriter, _ *http.Request) {
	w.Header().Set("Content-Type", "application/json; charset=utf-8")
	_ = json.NewEncoder(w).Encode(map[string]any{"notices": []any{}})
}