package store

import (
	"context"
	"errors"
	"fmt"
	"strings"
	"time"

	"github.com/jackc/pgx/v5"

	"github.com/loyaly/behavision-server/internal/api"
	"github.com/loyaly/behavision-server/internal/secret"
)

// Secrets decrypts values the server must hand back out - today, each site's
// broker password. Nil until configured, and every path that needs it says so
// rather than silently returning an empty credential.
func (s *Store) UseSecrets(b *secret.Box) { s.secrets = b }

// likePattern escapes the wildcards so a customer searching for "50%" finds
// the person called "50%" instead of matching everybody.
func likePattern(q string) string {
	r := strings.NewReplacer(`\`, `\\`, `%`, `\%`, `_`, `\_`)
	return "%" + r.Replace(q) + "%"
}

// searchNumber is the customer number behind a query, or 0 for a query that is
// not one.
//
// The reference is what staff now READ on screen - "V-13" - so it is what they
// paste into the search box, and matching only `label ILIKE '%V-13%'` finds
// nothing at all, because the stored label says "Visitor 13". A search that
// comes back empty for the identifier the product just showed you is worse
// than no search at all.
func searchNumber(query string) int64 {
	n, ok := api.ParseVisitorRef(query)
	if !ok {
		return 0
	}
	return n
}

func (s *Store) SearchVisitors(ctx context.Context, clientID, query string, limit int) (
	[]api.Customer, error) {

	rows, err := s.pool.Query(ctx, `
		SELECT v.id::text, v.number, v.label,
		       COALESCE(p.full_name, ''), COALESCE(p.phone, ''), COALESCE(p.email, ''),
		       v.visit_count, v.first_seen_at, v.last_seen_at,
		       (p.id IS NOT NULL),
		       EXISTS (SELECT 1 FROM consents c
		               WHERE c.visitor_id = v.id AND c.revoked_at IS NULL)
		FROM visitors v
		LEFT JOIN visitor_profiles p
		       ON p.visitor_id = v.id AND p.client_id = v.client_id
		WHERE v.client_id = $1 AND v.deleted_at IS NULL
		  AND ($2 = '' OR v.number = $5
		               OR v.label ILIKE $3 ESCAPE '\'
		               OR p.full_name ILIKE $3 ESCAPE '\'
		               OR p.phone     ILIKE $3 ESCAPE '\'
		               OR p.email     ILIKE $3 ESCAPE '\'
		               -- Notes are searched for ONE reason: a merge records the
		               -- phone and name it had to discard there, and a customer
		               -- reached by their old number is exactly who somebody is
		               -- looking for when they type it. Retained-but-unfindable
		               -- answers the letter of "nothing is lost" and not the point.
		               OR p.notes     ILIKE $3 ESCAPE '\')
		ORDER BY v.last_seen_at DESC NULLS LAST, v.first_seen_at DESC
		LIMIT $4`,
		clientID, strings.TrimSpace(query), likePattern(strings.TrimSpace(query)),
		limit, searchNumber(query))
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var out []api.Customer
	for rows.Next() {
		var c api.Customer
		var first time.Time
		var last *time.Time
		var number int64
		if err := rows.Scan(&c.ID, &number, &c.Label, &c.FullName, &c.Phone, &c.Email,
			&c.VisitCount, &first, &last, &c.HasProfile, &c.HasConsent); err != nil {
			return nil, err
		}
		c.Ref = api.VisitorRef(number)
		c.FirstSeenAt = first.UTC().Format(time.RFC3339)
		if last != nil {
			c.LastSeenAt = last.UTC().Format(time.RFC3339)
		}
		out = append(out, c)
	}
	return out, rows.Err()
}

func (s *Store) VisitorHistory(ctx context.Context, clientID, visitorID string, limit int) (
	[]api.VisitRow, error) {

	rows, err := s.pool.Query(ctx, `
		SELECT vi.id::text, vi.occurred_at, si.name, vi.camera_id,
		       vi.is_new_visitor, vi.similarity, vi.quality, vi.attributes,
		       pu.n, pu.total, pu.cur, pu.currencies
		FROM visits vi
		JOIN sites si ON si.id = vi.site_id
		-- LATERAL rather than a join onto purchases directly: two sales on one
		-- visit would otherwise return that visit twice and the customer would
		-- appear to have been in more often than they were.
		LEFT JOIN LATERAL (
		  SELECT count(*) AS n, sum(p.amount) AS total,
		         max(p.currency) AS cur, count(DISTINCT p.currency) AS currencies
		  FROM purchases p
		  WHERE p.visit_id = vi.id AND p.client_id = vi.client_id
		) pu ON true
		WHERE vi.client_id = $1 AND vi.visitor_id = $2::uuid
		ORDER BY vi.occurred_at DESC
		LIMIT $3`, clientID, visitorID, limit)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var out []api.VisitRow
	for rows.Next() {
		var v api.VisitRow
		var at time.Time
		var sim, qual, total *float64
		var nPurchases, nCurrencies int
		var cur *string
		if err := rows.Scan(&v.ID, &at, &v.Site, &v.CameraID, &v.IsNew,
			&sim, &qual, &v.Attributes,
			&nPurchases, &total, &cur, &nCurrencies); err != nil {
			return nil, err
		}
		v.Purchases = nPurchases
		// One currency or none. Mixed is left as a count with no figure
		// rather than a sum that means nothing.
		if nCurrencies == 1 && total != nil && cur != nil {
			v.Spend, v.Currency = *total, *cur
		}
		v.OccurredAt = at.UTC().Format(time.RFC3339)
		if sim != nil {
			v.Similarity = *sim
		}
		if qual != nil {
			v.Quality = *qual
		}
		out = append(out, v)
	}
	return out, rows.Err()
}

// SaveProfile writes the in-store form, and the consent record with it.
//
// One transaction: a name saved without its consent row is a customer whose
// personal data we hold with no record of being allowed to, which is the exact
// state the consents table exists to make impossible.
func (s *Store) SaveProfile(ctx context.Context, clientID string, p api.Profile,
	actor string) error {

	tx, err := s.pool.Begin(ctx)
	if err != nil {
		return err
	}
	defer tx.Rollback(ctx) //nolint:errcheck // no-op once committed

	// Scoped to the client, so an id from another tenant is simply not found -
	// the same answer as a typo, which is what it should look like.
	var exists bool
	err = tx.QueryRow(ctx, `
		SELECT true FROM visitors
		WHERE id = $1::uuid AND client_id = $2 AND deleted_at IS NULL`,
		p.VisitorID, clientID).Scan(&exists)
	if errors.Is(err, pgx.ErrNoRows) {
		return errors.New("no such visitor")
	}
	if err != nil {
		return err
	}

	var dob any
	if p.DateOfBirth != "" {
		dob = p.DateOfBirth
	}
	if _, err := tx.Exec(ctx, `
		INSERT INTO visitor_profiles (visitor_id, client_id, full_name, phone,
		                              email, gender, date_of_birth, notes,
		                              collected_by)
		VALUES ($1::uuid, $2, $3, $4, $5, $6, $7::date, $8, NULLIF($9, '')::uuid)
		ON CONFLICT (visitor_id) DO UPDATE SET
		    full_name     = EXCLUDED.full_name,
		    phone         = EXCLUDED.phone,
		    email         = EXCLUDED.email,
		    gender        = EXCLUDED.gender,
		    date_of_birth = EXCLUDED.date_of_birth,
		    notes         = EXCLUDED.notes,
		    collected_by  = EXCLUDED.collected_by,
		    updated_at    = now()`,
		p.VisitorID, clientID, p.FullName, p.Phone, p.Email, p.Gender,
		dob, p.Notes, actor); err != nil {
		return fmt.Errorf("save profile: %w", err)
	}

	if p.Consent {
		// Only if there is not already a live one. Re-saving the form must not
		// stack up consent records, or the audit trail stops being readable.
		if _, err := tx.Exec(ctx, `
			INSERT INTO consents (visitor_id, client_id, scope, method,
			                      collected_by, evidence)
			SELECT $1::uuid, $2, 'biometric', 'in_store_form',
			       NULLIF($3, '')::uuid, '{}'::jsonb
			WHERE NOT EXISTS (
			    SELECT 1 FROM consents
			    WHERE visitor_id = $1::uuid AND scope = 'biometric'
			      AND revoked_at IS NULL)`,
			p.VisitorID, clientID, actor); err != nil {
			return fmt.Errorf("record consent: %w", err)
		}
	} else {
		// Unticking the box is a withdrawal, and a withdrawal is a timestamp,
		// never a delete: the fact that they withdrew is itself the thing an
		// auditor asks to see.
		if _, err := tx.Exec(ctx, `
			UPDATE consents SET revoked_at = now()
			WHERE visitor_id = $1::uuid AND client_id = $2
			  AND scope = 'biometric' AND revoked_at IS NULL`,
			p.VisitorID, clientID); err != nil {
			return fmt.Errorf("revoke consent: %w", err)
		}
	}
	return tx.Commit(ctx)
}

// RecordPurchase books a sale against a customer.
//
// When no site is given it uses the one where this customer was most recently
// seen, which is what "the assistant on the floor just sold them something"
// means. If they have never been seen anywhere the caller is told to pass a
// site rather than being handed a foreign key error.
func (s *Store) RecordPurchase(ctx context.Context, clientID string,
	p api.PurchaseInput, actor string) error {

	tx, err := s.pool.Begin(ctx)
	if err != nil {
		return err
	}
	defer tx.Rollback(ctx) //nolint:errcheck

	var exists bool
	err = tx.QueryRow(ctx, `
		SELECT true FROM visitors
		WHERE id = $1::uuid AND client_id = $2 AND deleted_at IS NULL`,
		p.VisitorID, clientID).Scan(&exists)
	if errors.Is(err, pgx.ErrNoRows) {
		return errors.New("no such visitor")
	}
	if err != nil {
		return err
	}

	siteID := p.SiteID
	var visitID any
	if siteID == "" {
		var sid, vid *string
		err = tx.QueryRow(ctx, `
			SELECT site_id::text, id::text FROM visits
			WHERE client_id = $1 AND visitor_id = $2::uuid
			ORDER BY occurred_at DESC LIMIT 1`,
			clientID, p.VisitorID).Scan(&sid, &vid)
		if errors.Is(err, pgx.ErrNoRows) || sid == nil {
			return errors.New("no site for this visitor")
		}
		if err != nil {
			return err
		}
		siteID = *sid
		// Attaching the sale to the visit it belongs to is what makes
		// "did this visit convert" answerable at all, rather than only
		// "did this person ever buy".
		visitID = vid
	} else {
		// A site passed in must still belong to the caller's client.
		var ok bool
		err = tx.QueryRow(ctx,
			`SELECT true FROM sites WHERE id = $1::uuid AND client_id = $2`,
			siteID, clientID).Scan(&ok)
		if errors.Is(err, pgx.ErrNoRows) {
			return errors.New("no site for this visitor")
		}
		if err != nil {
			return err
		}
	}

	items := p.Items
	if items == nil {
		items = []string{}
	}
	if _, err := tx.Exec(ctx, `
		INSERT INTO purchases (client_id, site_id, visitor_id, visit_id, amount,
		                       currency, items, source, external_ref, recorded_by)
		VALUES ($1, $2::uuid, $3::uuid, $4::uuid, $5, $6, $7, $8, $9,
		        NULLIF($10, '')::uuid)`,
		clientID, siteID, p.VisitorID, visitID, p.Amount, p.Currency,
		items, p.Source, p.Notes, actor); err != nil {
		return fmt.Errorf("insert purchase: %w", err)
	}
	return tx.Commit(ctx)
}

// ---------------------------------------------------------------- enrolment

// RedeemEnrolment spends an installation code and returns the broker login.
//
// Single-use is enforced by the UPDATE itself: the `used_at IS NULL` predicate
// and the write are one statement, so two PCs racing on the same code cannot
// both win. Checking first and updating after would be exactly that race.
func (s *Store) RedeemEnrolment(ctx context.Context, hash []byte) (api.Enrolment, error) {
	var en api.Enrolment
	err := s.pool.QueryRow(ctx, `
		UPDATE site_enrolment_tokens
		SET used_at = now()
		WHERE token_hash = $1 AND used_at IS NULL AND expires_at > now()
		RETURNING client_id::text, site_id::text`, hash).
		Scan(&en.ClientID, &en.SiteID)
	if errors.Is(err, pgx.ErrNoRows) {
		return en, errors.New("enrolment token is unknown, expired or already used")
	}
	if err != nil {
		return en, err
	}

	var sealed []byte
	if err := s.pool.QueryRow(ctx, `
		SELECT si.name, si.slug, a.id::text, a.mqtt_username, a.mqtt_password_enc
		FROM sites si
		JOIN agents a ON a.site_id = si.id
		WHERE si.id = $1::uuid AND si.client_id = $2`,
		en.SiteID, en.ClientID).
		Scan(&en.SiteName, &en.SiteSlug, &en.AgentID, &en.MQTTUser, &sealed); err != nil {
		if errors.Is(err, pgx.ErrNoRows) {
			return en, errors.New("site has no agent provisioned - " +
				"create the broker user before issuing an enrolment token")
		}
		return en, err
	}
	if len(sealed) == 0 {
		return en, errors.New("site has no broker password stored")
	}
	if s.secrets == nil {
		return en, errors.New("BEHAVISION_SECRET_KEY is not configured, " +
			"so stored broker passwords cannot be read")
	}
	pass, err := s.secrets.OpenString(sealed, en.AgentID)
	if err != nil {
		return en, fmt.Errorf("broker password for %s: %w", en.SiteSlug, err)
	}
	en.MQTTPass = pass
	return en, nil
}

// SetAgentSecret stores a site's broker password, sealed to that agent's id.
// Used by provisioning, never by a request handler.
func (s *Store) SetAgentSecret(ctx context.Context, agentID, password string) error {
	if s.secrets == nil {
		return errors.New("BEHAVISION_SECRET_KEY is not configured")
	}
	sealed, err := s.secrets.SealString(password, agentID)
	if err != nil {
		return err
	}
	_, err = s.pool.Exec(ctx,
		`UPDATE agents SET mqtt_password_enc = $2 WHERE id = $1::uuid`,
		agentID, sealed)
	return err
}

// Audit never fails a request.
//
// A refused audit write is worth knowing about, but refusing the action it was
// recording is worse: it would mean an outage in the logging table stops staff
// serving customers.
func (s *Store) Audit(ctx context.Context, e api.AuditEntry) {
	detail := e.Detail
	if detail == nil {
		detail = map[string]any{}
	}
	if _, err := s.pool.Exec(ctx, `
		INSERT INTO audit_log (client_id, actor_id, actor_kind, action,
		                       entity, entity_id, detail)
		VALUES (NULLIF($1, '')::uuid, NULLIF($2, '')::uuid, $3, $4, $5, $6, $7)`,
		e.ClientID, e.ActorID, e.ActorKind, e.Action,
		e.Entity, e.EntityID, detail); err != nil {
		s.auditFailed(e.Action, err)
	}
}