package api

import (
	"context"
	"errors"
	"log/slog"
	"net/http"
	"time"

	"github.com/google/uuid"

	"github.com/alchemistkay/guestguard/internal/domain"
	"github.com/alchemistkay/guestguard/internal/storage"
)

// privacyHandler holds the GDPR-style "your data, your choice" endpoints:
// data export, account deletion, and terms-acceptance recording.
type privacyHandler struct {
	logger   *slog.Logger
	users    *storage.UserRepo
	events   *storage.EventRepo
	guests   *storage.GuestRepo
	tokens   *storage.TokenRepo
	rsvps    *storage.RSVPRepo
	access   *storage.AccessLogRepo
	notifs   *storage.DB // raw pool access for the export queries
	refresh  *storage.RefreshTokenRepo
}

// DataExport is the shape of the JSON the host downloads from
// GET /me/data-export. We don't paginate or stream — for the scale
// GuestGuard hosts have, a single response is reasonable. If a host
// ever has 100k+ access logs we'll switch to async + email-a-link.
type DataExport struct {
	ExportedAt time.Time           `json:"exported_at"`
	Format     string              `json:"format"`
	User       *domain.User        `json:"user"`
	Events     []*domain.Event     `json:"events"`
	Guests     []*domain.Guest     `json:"guests"`
	Tokens     []exportedToken     `json:"tokens"`
	RSVPs      []exportedRSVP      `json:"rsvps"`
	AccessLogs []exportedAccess    `json:"access_logs"`
	Notifs     []exportedNotif     `json:"notifications"`
}

type exportedToken struct {
	ID        uuid.UUID `json:"id"`
	GuestID   uuid.UUID `json:"guest_id"`
	ExpiresAt time.Time `json:"expires_at"`
	Status    string    `json:"status"`
	CreatedAt time.Time `json:"created_at"`
}
type exportedRSVP struct {
	ID          uuid.UUID `json:"id"`
	GuestID     uuid.UUID `json:"guest_id"`
	Response    string    `json:"response"`
	PlusOnes    int       `json:"plus_ones"`
	SubmittedAt time.Time `json:"submitted_at"`
}
type exportedAccess struct {
	ID         uuid.UUID `json:"id"`
	GuestID    uuid.UUID `json:"guest_id"`
	RiskScore  *int      `json:"risk_score,omitempty"`
	Flagged    bool      `json:"flagged"`
	CreatedAt  time.Time `json:"created_at"`
}
type exportedNotif struct {
	ID        uuid.UUID `json:"id"`
	GuestID   uuid.UUID `json:"guest_id"`
	Channel   string    `json:"channel"`
	Type      string    `json:"type"`
	Status    string    `json:"status"`
	CreatedAt time.Time `json:"created_at"`
}

// GET /me/data-export — returns every record the system holds about the
// authenticated user. The Content-Disposition header makes browsers
// offer a download rather than rendering inline.
func (h *privacyHandler) dataExport(w http.ResponseWriter, r *http.Request) {
	hostID, ok := hostFromContext(w, r)
	if !ok {
		return
	}

	user, err := h.users.GetByID(r.Context(), hostID)
	if err != nil {
		writeError(w, http.StatusInternalServerError, "failed to load user")
		return
	}

	export := DataExport{
		ExportedAt: time.Now().UTC(),
		Format:     "guestguard.v1",
		User:       user,
	}

	// Events the user hosts.
	events, err := h.events.List(r.Context(), hostID, 1000, 0)
	if err != nil {
		writeError(w, http.StatusInternalServerError, "failed to load events")
		return
	}
	export.Events = events

	// For each event, pull guests + tokens + rsvps + access_logs + notifications.
	for _, ev := range events {
		guests, err := h.guests.ListByEvent(r.Context(), ev.ID, 5000, 0)
		if err != nil {
			writeError(w, http.StatusInternalServerError, "failed to load guests")
			return
		}
		export.Guests = append(export.Guests, guests...)

		for _, g := range guests {
			// Token (at most one per guest, but query as a list for symmetry).
			if err := h.appendTokens(r.Context(), g.ID, &export); err != nil {
				h.logger.Warn("export: tokens", "err", err)
			}
			if err := h.appendRSVPs(r.Context(), g.ID, &export); err != nil {
				h.logger.Warn("export: rsvps", "err", err)
			}
			if err := h.appendAccess(r.Context(), g.ID, &export); err != nil {
				h.logger.Warn("export: access", "err", err)
			}
			if err := h.appendNotifs(r.Context(), g.ID, &export); err != nil {
				h.logger.Warn("export: notifs", "err", err)
			}
		}
	}

	w.Header().Set("Content-Type", "application/json; charset=utf-8")
	w.Header().Set("Content-Disposition", `attachment; filename="guestguard-data-export.json"`)
	writeJSON(w, http.StatusOK, export)
}

func (h *privacyHandler) appendTokens(ctx context.Context, guestID uuid.UUID, out *DataExport) error {
	rows, err := h.notifs.Pool.Query(ctx, `
        SELECT id, guest_id, expires_at, status, created_at
        FROM tokens WHERE guest_id = $1
    `, guestID)
	if err != nil {
		return err
	}
	defer rows.Close()
	for rows.Next() {
		var t exportedToken
		if err := rows.Scan(&t.ID, &t.GuestID, &t.ExpiresAt, &t.Status, &t.CreatedAt); err != nil {
			return err
		}
		out.Tokens = append(out.Tokens, t)
	}
	return rows.Err()
}
func (h *privacyHandler) appendRSVPs(ctx context.Context, guestID uuid.UUID, out *DataExport) error {
	rows, err := h.notifs.Pool.Query(ctx, `
        SELECT id, guest_id, response::text, plus_ones, submitted_at
        FROM rsvps WHERE guest_id = $1
    `, guestID)
	if err != nil {
		return err
	}
	defer rows.Close()
	for rows.Next() {
		var r exportedRSVP
		if err := rows.Scan(&r.ID, &r.GuestID, &r.Response, &r.PlusOnes, &r.SubmittedAt); err != nil {
			return err
		}
		out.RSVPs = append(out.RSVPs, r)
	}
	return rows.Err()
}
func (h *privacyHandler) appendAccess(ctx context.Context, guestID uuid.UUID, out *DataExport) error {
	rows, err := h.notifs.Pool.Query(ctx, `
        SELECT id, guest_id, risk_score, flagged, created_at
        FROM access_logs WHERE guest_id = $1
    `, guestID)
	if err != nil {
		return err
	}
	defer rows.Close()
	for rows.Next() {
		var a exportedAccess
		var rs *int
		if err := rows.Scan(&a.ID, &a.GuestID, &rs, &a.Flagged, &a.CreatedAt); err != nil {
			return err
		}
		a.RiskScore = rs
		out.AccessLogs = append(out.AccessLogs, a)
	}
	return rows.Err()
}
func (h *privacyHandler) appendNotifs(ctx context.Context, guestID uuid.UUID, out *DataExport) error {
	rows, err := h.notifs.Pool.Query(ctx, `
        SELECT id, guest_id, channel::text, type::text, status::text, created_at
        FROM notifications WHERE guest_id = $1
    `, guestID)
	if err != nil {
		return err
	}
	defer rows.Close()
	for rows.Next() {
		var n exportedNotif
		if err := rows.Scan(&n.ID, &n.GuestID, &n.Channel, &n.Type, &n.Status, &n.CreatedAt); err != nil {
			return err
		}
		out.Notifs = append(out.Notifs, n)
	}
	return rows.Err()
}

// DELETE /me — soft-deletes the host's account. All sessions are
// revoked immediately. A hard delete happens via a separate cron 30
// days later (TBD ops work). The user is logged out from all devices
// as a side effect of revoking the refresh tokens.
func (h *privacyHandler) deleteMe(w http.ResponseWriter, r *http.Request) {
	hostID, ok := hostFromContext(w, r)
	if !ok {
		return
	}
	if err := h.users.SoftDelete(r.Context(), hostID); err != nil {
		if errors.Is(err, domain.ErrUserNotFound) {
			writeError(w, http.StatusNotFound, "user not found")
			return
		}
		writeError(w, http.StatusInternalServerError, "failed to delete account")
		return
	}
	// Best-effort: revoke refresh tokens so other sessions log out too.
	// Failure here is logged but doesn't roll back the soft-delete — the
	// access tokens (JWT) will still expire on their own ~15 minute TTL.
	if err := h.refresh.RevokeAllForUser(r.Context(), hostID); err != nil {
		h.logger.Warn("delete-me: revoke refresh tokens", "err", err, "user_id", hostID)
	}
	w.WriteHeader(http.StatusNoContent)
}

// POST /me/accept-terms — records that the authenticated user accepts
// the current ToS + privacy policy. Idempotent. Used by both the
// onboarding gate (existing accounts created before T&C were enforced)
// and any future "we updated our terms" re-acceptance flow.
func (h *privacyHandler) acceptTerms(w http.ResponseWriter, r *http.Request) {
	hostID, ok := hostFromContext(w, r)
	if !ok {
		return
	}
	if err := h.users.AcceptTerms(r.Context(), hostID); err != nil {
		if errors.Is(err, domain.ErrUserNotFound) {
			writeError(w, http.StatusNotFound, "user not found")
			return
		}
		writeError(w, http.StatusInternalServerError, "failed to record acceptance")
		return
	}
	writeJSON(w, http.StatusOK, map[string]string{"status": "accepted"})
}