package saas

import (
	"context"
	"crypto/rand"
	"crypto/sha256"
	"encoding/base64"
	"encoding/hex"
	"errors"
	"fmt"
	"strings"
	"time"

	"data-terminal-cloud/internal/audit"
	"data-terminal-cloud/internal/database"
	"data-terminal-cloud/internal/identity"

	"github.com/jackc/pgx/v5"
)

var (
	ErrInvitationInvalid = errors.New("member invitation is invalid")
	ErrMemberExists      = errors.New("active household member already exists")
	ErrOwnerProtected    = errors.New("household owner must be transferred first")
)

type HouseholdMember struct {
	ID          string        `json:"id"`
	UserID      string        `json:"user_id"`
	DisplayName string        `json:"display_name"`
	Role        identity.Role `json:"role"`
	Status      string        `json:"status"`
	JoinedAt    time.Time     `json:"joined_at"`
	RemovedAt   *time.Time    `json:"removed_at,omitempty"`
	Version     int64         `json:"version"`
	IsOwner     bool          `json:"is_owner"`
}

type MemberInvitation struct {
	ID          string        `json:"id"`
	HouseholdID string        `json:"household_id"`
	InviteeHint string        `json:"invitee_hint,omitempty"`
	Role        identity.Role `json:"role"`
	ExpiresAt   time.Time     `json:"expires_at"`
	UsedAt      *time.Time    `json:"used_at,omitempty"`
	RevokedAt   *time.Time    `json:"revoked_at,omitempty"`
	CreatedAt   time.Time     `json:"created_at"`
	Status      string        `json:"status"`
	Token       string        `json:"token,omitempty"`
}

type MemberInvitationPreview struct {
	TenantID      string        `json:"tenant_id"`
	TenantName    string        `json:"tenant_name"`
	HouseholdID   string        `json:"household_id"`
	HouseholdName string        `json:"household_name"`
	InviteeHint   string        `json:"invitee_hint,omitempty"`
	Role          identity.Role `json:"role"`
	ExpiresAt     time.Time     `json:"expires_at"`
}

func (s *Service) PreviewMemberInvitation(ctx context.Context, token string) (MemberInvitationPreview, error) {
	digest := sha256.Sum256([]byte(strings.TrimSpace(token)))
	var result MemberInvitationPreview
	var usedAt, revokedAt *time.Time
	err := s.pool.QueryRow(ctx, `
		SELECT t.public_id::text,t.name,h.public_id::text,h.name,COALESCE(mi.invitee_hint,''),mi.role,mi.expires_at,mi.used_at,mi.revoked_at
		FROM member_invitation mi
		JOIN household h ON h.id=mi.household_id AND h.tenant_id=mi.tenant_id AND h.status='active'
		JOIN tenant t ON t.id=mi.tenant_id AND t.status='active'
		WHERE mi.token_digest=$1`, hex.EncodeToString(digest[:])).Scan(&result.TenantID, &result.TenantName, &result.HouseholdID, &result.HouseholdName, &result.InviteeHint, &result.Role, &result.ExpiresAt, &usedAt, &revokedAt)
	if errors.Is(err, pgx.ErrNoRows) {
		return MemberInvitationPreview{}, ErrInvitationInvalid
	}
	if err != nil {
		return MemberInvitationPreview{}, fmt.Errorf("preview member invitation: %w", err)
	}
	if usedAt != nil || revokedAt != nil || !result.ExpiresAt.After(time.Now()) {
		return MemberInvitationPreview{}, ErrInvitationInvalid
	}
	return result, nil
}

func (s *Service) ListHouseholdMembers(ctx context.Context, principal identity.Principal, householdPublicID string) ([]HouseholdMember, error) {
	access, err := resolveHouseholdAccess(ctx, s.pool, principal, householdPublicID, identity.CapabilityHouseholdRead, false)
	if err != nil {
		return nil, err
	}
	rows, err := s.pool.Query(ctx, `
		SELECT hm.public_id::text, ua.public_id::text, ua.display_name, hm.role, hm.status,
			hm.joined_at, hm.removed_at, hm.version, hm.user_id=h.owner_user_id
		FROM household_member hm
		JOIN user_account ua ON ua.id=hm.user_id AND ua.tenant_id=hm.tenant_id
		JOIN household h ON h.id=hm.household_id AND h.tenant_id=hm.tenant_id
		WHERE hm.tenant_id=$1::uuid AND hm.household_id=$2::uuid AND hm.status='active'
		ORDER BY (hm.user_id=h.owner_user_id) DESC, hm.joined_at, hm.public_id`, access.tenantID, access.householdID)
	if err != nil {
		return nil, fmt.Errorf("list household members: %w", err)
	}
	defer rows.Close()
	items := make([]HouseholdMember, 0)
	for rows.Next() {
		item, err := scanHouseholdMember(rows)
		if err != nil {
			return nil, fmt.Errorf("scan household member: %w", err)
		}
		items = append(items, item)
	}
	if err := rows.Err(); err != nil {
		return nil, fmt.Errorf("iterate household members: %w", err)
	}
	return items, nil
}

func (s *Service) ListMemberInvitations(ctx context.Context, principal identity.Principal, householdPublicID string) ([]MemberInvitation, error) {
	access, err := resolveHouseholdAccess(ctx, s.pool, principal, householdPublicID, identity.CapabilityMemberManage, false)
	if err != nil {
		return nil, err
	}
	rows, err := s.pool.Query(ctx, `
		SELECT public_id::text,$1::text,COALESCE(invitee_hint,''),role,expires_at,used_at,revoked_at,created_at
		FROM member_invitation WHERE tenant_id=$2::uuid AND household_id=$3::uuid
		ORDER BY created_at DESC, public_id`, householdPublicID, access.tenantID, access.householdID)
	if err != nil {
		return nil, fmt.Errorf("list member invitations: %w", err)
	}
	defer rows.Close()
	items := make([]MemberInvitation, 0)
	for rows.Next() {
		item, err := scanInvitation(rows)
		if err != nil {
			return nil, fmt.Errorf("scan member invitation: %w", err)
		}
		items = append(items, item)
	}
	if err := rows.Err(); err != nil {
		return nil, fmt.Errorf("iterate member invitations: %w", err)
	}
	return items, nil
}

func (s *Service) CreateMemberInvitation(ctx context.Context, principal identity.Principal, householdPublicID, inviteeHint string, role identity.Role, expiresAt time.Time, requestID string) (MemberInvitation, error) {
	tokenBytes := make([]byte, 32)
	if _, err := rand.Read(tokenBytes); err != nil {
		return MemberInvitation{}, fmt.Errorf("generate invitation token: %w", err)
	}
	token := base64.RawURLEncoding.EncodeToString(tokenBytes)
	digest := sha256.Sum256([]byte(token))
	var result MemberInvitation
	err := database.Transact(ctx, s.pool, func(tx pgx.Tx) error {
		access, err := resolveHouseholdAccess(ctx, tx, principal, householdPublicID, identity.CapabilityMemberManage, true)
		if err != nil {
			return err
		}
		row := tx.QueryRow(ctx, `
			INSERT INTO member_invitation (tenant_id,household_id,invitee_hint,token_digest,role,expires_at,created_by)
			VALUES ($1::uuid,$2::uuid,NULLIF($3,''),$4,$5,$6,$7::uuid)
			RETURNING public_id::text,$8::text,COALESCE(invitee_hint,''),role,expires_at,used_at,revoked_at,created_at`,
			access.tenantID, access.householdID, inviteeHint, hex.EncodeToString(digest[:]), role, expiresAt, access.userID, householdPublicID)
		result, err = scanInvitation(row)
		if err != nil {
			return fmt.Errorf("insert member invitation: %w", err)
		}
		result.Token = token
		return s.audit.Record(ctx, tx, audit.Event{
			TenantID: strPtr(access.tenantID), ActorType: "user", ActorPublicID: strPtr(access.userPublicID),
			Action: "member.invitation.create", ResourceType: "member_invitation", ResourceID: strPtr(result.ID),
			RequestID: requestID, Result: "success", Detail: map[string]any{"household_id": householdPublicID, "role": role, "expires_at": expiresAt},
		})
	})
	return result, err
}

func (s *Service) RevokeMemberInvitation(ctx context.Context, principal identity.Principal, householdPublicID, invitationPublicID, requestID string) (MemberInvitation, error) {
	var result MemberInvitation
	err := database.Transact(ctx, s.pool, func(tx pgx.Tx) error {
		access, err := resolveHouseholdAccess(ctx, tx, principal, householdPublicID, identity.CapabilityMemberManage, true)
		if err != nil {
			return err
		}
		row := tx.QueryRow(ctx, `
			UPDATE member_invitation SET revoked_at=COALESCE(revoked_at,now())
			WHERE public_id=$1::uuid AND tenant_id=$2::uuid AND household_id=$3::uuid AND used_at IS NULL
			RETURNING public_id::text,$4::text,COALESCE(invitee_hint,''),role,expires_at,used_at,revoked_at,created_at`,
			invitationPublicID, access.tenantID, access.householdID, householdPublicID)
		result, err = scanInvitation(row)
		if errors.Is(err, pgx.ErrNoRows) {
			return ErrNotFound
		}
		if err != nil {
			return fmt.Errorf("revoke member invitation: %w", err)
		}
		return s.audit.Record(ctx, tx, audit.Event{
			TenantID: strPtr(access.tenantID), ActorType: "user", ActorPublicID: strPtr(access.userPublicID),
			Action: "member.invitation.revoke", ResourceType: "member_invitation", ResourceID: strPtr(result.ID),
			RequestID: requestID, Result: "success", Detail: map[string]any{"household_id": householdPublicID},
		})
	})
	return result, err
}

func (s *Service) AcceptMemberInvitation(ctx context.Context, principal identity.Principal, token, requestID string) (HouseholdMember, bool, error) {
	digest := sha256.Sum256([]byte(token))
	var result HouseholdMember
	var replayed bool
	var failureTenantID, failureUserPublicID, failureInvitationPublicID, failureHouseholdPublicID string
	err := database.Transact(ctx, s.pool, func(tx pgx.Tx) error {
		var invitationID, invitationPublicID, tenantID, householdID, householdPublicID, role string
		var expiresAt time.Time
		var usedAt, revokedAt *time.Time
		err := tx.QueryRow(ctx, `
			SELECT mi.id::text,mi.public_id::text,mi.tenant_id::text,mi.household_id::text,h.public_id::text,mi.role,mi.expires_at,mi.used_at,mi.revoked_at
			FROM member_invitation mi JOIN household h ON h.id=mi.household_id AND h.tenant_id=mi.tenant_id AND h.status='active'
			WHERE mi.token_digest=$1 FOR UPDATE OF mi`, hex.EncodeToString(digest[:])).Scan(
			&invitationID, &invitationPublicID, &tenantID, &householdID, &householdPublicID, &role, &expiresAt, &usedAt, &revokedAt)
		if errors.Is(err, pgx.ErrNoRows) {
			return ErrInvitationInvalid
		}
		if err != nil {
			return fmt.Errorf("resolve member invitation: %w", err)
		}
		var userID, userPublicID string
		if err := tx.QueryRow(ctx, `
			SELECT id::text,public_id::text FROM user_account
			WHERE tenant_id=$1::uuid AND oidc_issuer=$2 AND oidc_subject=$3 AND status='active'`,
			tenantID, principal.Issuer, principal.Subject).Scan(&userID, &userPublicID); errors.Is(err, pgx.ErrNoRows) {
			displayName := strings.TrimSpace(principal.DisplayName)
			if displayName == "" {
				displayName = strings.TrimSpace(principal.PreferredUsername)
			}
			if displayName == "" {
				displayName = "受邀家庭成员"
			}
			err = tx.QueryRow(ctx, `
				INSERT INTO user_account (tenant_id,oidc_issuer,oidc_subject,display_name,status,last_login_at)
				VALUES ($1::uuid,$2,$3,$4,'active',now())
				ON CONFLICT (tenant_id,oidc_issuer,oidc_subject) DO NOTHING
				RETURNING id::text,public_id::text`, tenantID, principal.Issuer, principal.Subject, displayName).Scan(&userID, &userPublicID)
			if errors.Is(err, pgx.ErrNoRows) {
				return ErrAccessDenied
			}
			if err != nil {
				return fmt.Errorf("create invited tenant account: %w", err)
			}
		} else if err != nil {
			return fmt.Errorf("resolve invitation account: %w", err)
		}
		failureTenantID, failureUserPublicID = tenantID, userPublicID
		failureInvitationPublicID, failureHouseholdPublicID = invitationPublicID, householdPublicID
		if usedAt != nil {
			return ErrInvitationInvalid
		}
		if revokedAt != nil || !expiresAt.After(time.Now()) {
			return ErrInvitationInvalid
		}
		var active bool
		if err := tx.QueryRow(ctx, `SELECT EXISTS(SELECT 1 FROM household_member WHERE household_id=$1::uuid AND user_id=$2::uuid AND status='active')`, householdID, userID).Scan(&active); err != nil {
			return fmt.Errorf("check existing household member: %w", err)
		}
		if active {
			return ErrMemberExists
		}
		row := tx.QueryRow(ctx, `
			INSERT INTO household_member (tenant_id,household_id,user_id,role,status)
			VALUES ($1::uuid,$2::uuid,$3::uuid,$4,'active')
			RETURNING public_id::text,$5::text,(SELECT display_name FROM user_account WHERE id=$3::uuid),role,status,joined_at,removed_at,version,false`,
			tenantID, householdID, userID, role, userPublicID)
		result, err = scanHouseholdMember(row)
		if err != nil {
			return fmt.Errorf("insert invited household member: %w", err)
		}
		if _, err := tx.Exec(ctx, `UPDATE member_invitation SET used_at=now() WHERE id=$1::uuid`, invitationID); err != nil {
			return fmt.Errorf("consume member invitation: %w", err)
		}
		return s.audit.Record(ctx, tx, audit.Event{
			TenantID: strPtr(tenantID), ActorType: "user", ActorPublicID: strPtr(userPublicID),
			Action: "member.invitation.accept", ResourceType: "household_member", ResourceID: strPtr(result.ID),
			RequestID: requestID, Result: "success", Detail: map[string]any{"household_id": householdPublicID, "role": role},
		})
	})
	if errors.Is(err, ErrInvitationInvalid) && failureTenantID != "" {
		auditErr := database.Transact(ctx, s.pool, func(tx pgx.Tx) error {
			return s.audit.Record(ctx, tx, audit.Event{
				TenantID: strPtr(failureTenantID), ActorType: "user", ActorPublicID: strPtr(failureUserPublicID),
				Action: "member.invitation.accept", ResourceType: "member_invitation", ResourceID: strPtr(failureInvitationPublicID),
				RequestID: requestID, Result: "failure", Detail: map[string]any{"household_id": failureHouseholdPublicID, "reason": "invalid_expired_revoked_or_used"},
			})
		})
		if auditErr != nil {
			return HouseholdMember{}, false, fmt.Errorf("record failed invitation acceptance: %w", auditErr)
		}
	}
	return result, replayed, err
}

func (s *Service) PatchHouseholdMemberRole(ctx context.Context, principal identity.Principal, householdPublicID, memberPublicID string, role identity.Role, expectedVersion int64, requestID string) (HouseholdMember, error) {
	var result HouseholdMember
	err := database.Transact(ctx, s.pool, func(tx pgx.Tx) error {
		access, err := resolveHouseholdAccess(ctx, tx, principal, householdPublicID, identity.CapabilityMemberManage, true)
		if err != nil {
			return err
		}
		var targetID, targetUserID, currentRole string
		var version int64
		if err := tx.QueryRow(ctx, `SELECT id::text,user_id::text,role,version FROM household_member WHERE public_id=$1::uuid AND household_id=$2::uuid AND tenant_id=$3::uuid AND status='active' FOR UPDATE`, memberPublicID, access.householdID, access.tenantID).Scan(&targetID, &targetUserID, &currentRole, &version); errors.Is(err, pgx.ErrNoRows) {
			return ErrNotFound
		} else if err != nil {
			return fmt.Errorf("resolve household member: %w", err)
		}
		if currentRole == string(identity.RoleOwner) {
			return ErrOwnerProtected
		}
		if version != expectedVersion {
			return ErrVersionConflict
		}
		row := tx.QueryRow(ctx, `
			UPDATE household_member hm SET role=$1,version=hm.version+1,updated_at=now()
			FROM user_account ua, household h
			WHERE hm.id=$2::uuid AND ua.id=hm.user_id AND h.id=hm.household_id
			RETURNING hm.public_id::text,ua.public_id::text,ua.display_name,hm.role,hm.status,hm.joined_at,hm.removed_at,hm.version,hm.user_id=h.owner_user_id`, role, targetID)
		result, err = scanHouseholdMember(row)
		if err != nil {
			return fmt.Errorf("update household member role: %w", err)
		}
		return s.audit.Record(ctx, tx, audit.Event{
			TenantID: strPtr(access.tenantID), ActorType: "user", ActorPublicID: strPtr(access.userPublicID),
			Action: "household_member.role.update", ResourceType: "household_member", ResourceID: strPtr(result.ID), RequestID: requestID,
			Result: "success", Detail: map[string]any{"household_id": householdPublicID, "from_role": currentRole, "to_role": role},
		})
	})
	return result, err
}

func (s *Service) RemoveHouseholdMember(ctx context.Context, principal identity.Principal, householdPublicID, memberPublicID string, expectedVersion int64, requestID string) (HouseholdMember, error) {
	var result HouseholdMember
	err := database.Transact(ctx, s.pool, func(tx pgx.Tx) error {
		access, err := resolveHouseholdAccess(ctx, tx, principal, householdPublicID, identity.CapabilityMemberManage, true)
		if err != nil {
			return err
		}
		row := tx.QueryRow(ctx, `
			SELECT hm.public_id::text,ua.public_id::text,ua.display_name,hm.role,hm.status,hm.joined_at,hm.removed_at,hm.version,hm.user_id=h.owner_user_id
			FROM household_member hm JOIN user_account ua ON ua.id=hm.user_id JOIN household h ON h.id=hm.household_id
			WHERE hm.public_id=$1::uuid AND hm.household_id=$2::uuid AND hm.tenant_id=$3::uuid AND hm.status='active' FOR UPDATE OF hm`, memberPublicID, access.householdID, access.tenantID)
		current, err := scanHouseholdMember(row)
		if errors.Is(err, pgx.ErrNoRows) {
			return ErrNotFound
		}
		if err != nil {
			return fmt.Errorf("resolve household member removal: %w", err)
		}
		if current.IsOwner {
			return ErrOwnerProtected
		}
		if current.Version != expectedVersion {
			return ErrVersionConflict
		}
		row = tx.QueryRow(ctx, `
			UPDATE household_member hm SET status='removed',removed_at=now(),version=hm.version+1,updated_at=now()
			FROM user_account ua WHERE hm.public_id=$1::uuid AND ua.id=hm.user_id
			RETURNING hm.public_id::text,ua.public_id::text,ua.display_name,hm.role,hm.status,hm.joined_at,hm.removed_at,hm.version,false`, memberPublicID)
		result, err = scanHouseholdMember(row)
		if err != nil {
			return fmt.Errorf("remove household member: %w", err)
		}
		return s.audit.Record(ctx, tx, audit.Event{
			TenantID: strPtr(access.tenantID), ActorType: "user", ActorPublicID: strPtr(access.userPublicID),
			Action: "household_member.remove", ResourceType: "household_member", ResourceID: strPtr(result.ID), RequestID: requestID,
			Result: "success", Detail: map[string]any{"household_id": householdPublicID, "role": current.Role},
		})
	})
	return result, err
}

func (s *Service) TransferHouseholdOwnership(ctx context.Context, principal identity.Principal, householdPublicID, targetMemberPublicID string, expectedVersion int64, requestID string) (Household, error) {
	var result Household
	err := database.Transact(ctx, s.pool, func(tx pgx.Tx) error {
		access, err := resolveHouseholdAccess(ctx, tx, principal, householdPublicID, identity.CapabilityOwnershipTransfer, true)
		if err != nil {
			return err
		}
		if access.version != expectedVersion {
			return ErrVersionConflict
		}
		var targetUserID, targetRole string
		if err := tx.QueryRow(ctx, `SELECT user_id::text,role FROM household_member WHERE public_id=$1::uuid AND tenant_id=$2::uuid AND household_id=$3::uuid AND status='active' FOR UPDATE`, targetMemberPublicID, access.tenantID, access.householdID).Scan(&targetUserID, &targetRole); errors.Is(err, pgx.ErrNoRows) {
			return ErrNotFound
		} else if err != nil {
			return fmt.Errorf("resolve ownership target: %w", err)
		}
		if targetUserID == access.userID {
			return ErrMemberExists
		}
		if _, err := tx.Exec(ctx, `UPDATE household_member SET role='admin',version=version+1,updated_at=now() WHERE household_id=$1::uuid AND user_id=$2::uuid AND status='active'`, access.householdID, access.userID); err != nil {
			return fmt.Errorf("demote former household owner: %w", err)
		}
		if _, err := tx.Exec(ctx, `UPDATE household_member SET role='owner',version=version+1,updated_at=now() WHERE household_id=$1::uuid AND user_id=$2::uuid AND status='active'`, access.householdID, targetUserID); err != nil {
			return fmt.Errorf("promote household owner: %w", err)
		}
		if err := tx.QueryRow(ctx, `
			UPDATE household SET owner_user_id=$1::uuid,version=version+1,updated_at=now() WHERE id=$2::uuid
			RETURNING public_id::text,$3::text,name,status,version,created_at,updated_at`, targetUserID, access.householdID, access.tenantPublicID).Scan(
			&result.ID, &result.TenantID, &result.Name, &result.Status, &result.Version, &result.CreatedAt, &result.UpdatedAt); err != nil {
			return fmt.Errorf("transfer household ownership: %w", err)
		}
		result.Role = identity.RoleAdmin
		result.Capabilities = identity.CapabilitiesForRole(result.Role)
		return s.audit.Record(ctx, tx, audit.Event{
			TenantID: strPtr(access.tenantID), ActorType: "user", ActorPublicID: strPtr(access.userPublicID),
			Action: "household.ownership.transfer", ResourceType: "household", ResourceID: strPtr(result.ID), RequestID: requestID,
			Result: "success", Detail: map[string]any{"target_member_id": targetMemberPublicID, "target_previous_role": targetRole, "version": result.Version},
		})
	})
	return result, err
}

func scanHouseholdMember(row rowScanner) (HouseholdMember, error) {
	var item HouseholdMember
	var role string
	if err := row.Scan(&item.ID, &item.UserID, &item.DisplayName, &role, &item.Status, &item.JoinedAt, &item.RemovedAt, &item.Version, &item.IsOwner); err != nil {
		return HouseholdMember{}, err
	}
	item.Role = identity.Role(role)
	return item, nil
}

func scanInvitation(row rowScanner) (MemberInvitation, error) {
	var item MemberInvitation
	var role string
	if err := row.Scan(&item.ID, &item.HouseholdID, &item.InviteeHint, &role, &item.ExpiresAt, &item.UsedAt, &item.RevokedAt, &item.CreatedAt); err != nil {
		return MemberInvitation{}, err
	}
	item.Role = identity.Role(role)
	switch {
	case item.UsedAt != nil:
		item.Status = "used"
	case item.RevokedAt != nil:
		item.Status = "revoked"
	case !item.ExpiresAt.After(time.Now()):
		item.Status = "expired"
	default:
		item.Status = "pending"
	}
	return item, nil
}