package ent

import (
	"context"
	"database/sql"
	"errors"
	"fmt"
	"strings"
	"time"

	"github.com/google/uuid"
	"github.com/jackc/pgx/v5"

	domain "knowfoolery/backend/services/user-service/internal/domain/user"
	sharederrors "knowfoolery/backend/shared/domain/errors"
	sharedtypes "knowfoolery/backend/shared/domain/types"
)

// UserRepository implements user storage on PostgreSQL.
type UserRepository struct {
	client *Client
}

// NewUserRepository creates a new user repository.
func NewUserRepository(client *Client) *UserRepository {
	return &UserRepository{client: client}
}

// EnsureSchema creates service tables if missing.
func (r *UserRepository) EnsureSchema(ctx context.Context) error {
	const ddl = `
CREATE TABLE IF NOT EXISTS users (
  id UUID PRIMARY KEY,
  zitadel_user_id VARCHAR(128) UNIQUE,
  email VARCHAR(320) NOT NULL UNIQUE,
  email_verified BOOLEAN NOT NULL DEFAULT FALSE,
  display_name VARCHAR(50) NOT NULL,
  consent_version VARCHAR(32) NOT NULL,
  consent_given_at TIMESTAMPTZ NOT NULL,
  consent_source VARCHAR(32) NOT NULL DEFAULT 'web',
  created_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
  updated_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
  deleted_at TIMESTAMPTZ NULL
);
CREATE INDEX IF NOT EXISTS idx_users_deleted_at ON users (deleted_at);
CREATE INDEX IF NOT EXISTS idx_users_created_at ON users (created_at DESC);

CREATE TABLE IF NOT EXISTS user_audit_log (
  id UUID PRIMARY KEY,
  actor_user_id VARCHAR(128),
  target_user_id UUID NOT NULL,
  action VARCHAR(64) NOT NULL,
  metadata_json JSONB NOT NULL DEFAULT '{}'::jsonb,
  created_at TIMESTAMPTZ NOT NULL DEFAULT NOW()
);
CREATE INDEX IF NOT EXISTS idx_user_audit_log_target_user_id ON user_audit_log (target_user_id, created_at DESC);
`
	_, err := r.client.Pool.Exec(ctx, ddl)
	return err
}

// Create inserts a new user.
func (r *UserRepository) Create(ctx context.Context, user *domain.User) (*domain.User, error) {
	id := uuid.NewString()
	now := time.Now().UTC()

	const q = `
INSERT INTO users (
  id, zitadel_user_id, email, email_verified, display_name,
  consent_version, consent_given_at, consent_source,
  created_at, updated_at
)
VALUES ($1,$2,$3,$4,$5,$6,$7,$8,$9,$10)
RETURNING id, zitadel_user_id, email, email_verified, display_name,
  consent_version, consent_given_at, consent_source,
  created_at, updated_at, deleted_at`

	row := r.client.Pool.QueryRow(ctx, q,
		id,
		nullIfEmpty(user.ZitadelUserID),
		user.Email,
		user.EmailVerified,
		user.DisplayName,
		user.ConsentVersion,
		user.ConsentGivenAt,
		user.ConsentSource,
		now,
		now,
	)

	created, err := scanUser(row)
	if err != nil {
		if isUniqueViolation(err) {
			return nil, sharederrors.Wrap(sharederrors.CodeUserAlreadyExists, "user already exists", err)
		}
		return nil, err
	}
	return created, nil
}

// GetByID fetches a user by ID and excludes soft-deleted users.
func (r *UserRepository) GetByID(ctx context.Context, id string) (*domain.User, error) {
	const q = `
SELECT id, zitadel_user_id, email, email_verified, display_name,
  consent_version, consent_given_at, consent_source,
  created_at, updated_at, deleted_at
FROM users
WHERE id=$1 AND deleted_at IS NULL`

	row := r.client.Pool.QueryRow(ctx, q, id)
	u, err := scanUser(row)
	if err != nil {
		if errors.Is(err, pgx.ErrNoRows) {
			return nil, sharederrors.Wrap(sharederrors.CodeUserNotFound, "user not found", err)
		}
		return nil, err
	}
	return u, nil
}

// GetByEmail fetches a non-deleted user by email.
func (r *UserRepository) GetByEmail(ctx context.Context, email string) (*domain.User, error) {
	const q = `
SELECT id, zitadel_user_id, email, email_verified, display_name,
  consent_version, consent_given_at, consent_source,
  created_at, updated_at, deleted_at
FROM users
WHERE email=$1 AND deleted_at IS NULL`

	row := r.client.Pool.QueryRow(ctx, q, strings.ToLower(email))
	u, err := scanUser(row)
	if err != nil {
		if errors.Is(err, pgx.ErrNoRows) {
			return nil, sharederrors.Wrap(sharederrors.CodeUserNotFound, "user not found", err)
		}
		return nil, err
	}
	return u, nil
}

// GetByZitadelUserID fetches a non-deleted user by identity id.
func (r *UserRepository) GetByZitadelUserID(ctx context.Context, zitadelUserID string) (*domain.User, error) {
	const q = `
SELECT id, zitadel_user_id, email, email_verified, display_name,
  consent_version, consent_given_at, consent_source,
  created_at, updated_at, deleted_at
FROM users
WHERE zitadel_user_id=$1 AND deleted_at IS NULL`

	row := r.client.Pool.QueryRow(ctx, q, zitadelUserID)
	u, err := scanUser(row)
	if err != nil {
		if errors.Is(err, pgx.ErrNoRows) {
			return nil, sharederrors.Wrap(sharederrors.CodeUserNotFound, "user not found", err)
		}
		return nil, err
	}
	return u, nil
}

// UpdateProfile updates mutable profile fields.
func (r *UserRepository) UpdateProfile(
	ctx context.Context,
	id string,
	displayName string,
	consent domain.ConsentRecord,
) (*domain.User, error) {
	const q = `
UPDATE users
SET display_name=$2,
    consent_version=$3,
    consent_given_at=$4,
    consent_source=$5,
    updated_at=NOW()
WHERE id=$1 AND deleted_at IS NULL
RETURNING id, zitadel_user_id, email, email_verified, display_name,
  consent_version, consent_given_at, consent_source,
  created_at, updated_at, deleted_at`

	row := r.client.Pool.QueryRow(ctx, q,
		id,
		displayName,
		consent.Version,
		consent.GivenAt,
		consent.Source,
	)

	u, err := scanUser(row)
	if err != nil {
		if errors.Is(err, pgx.ErrNoRows) {
			return nil, sharederrors.Wrap(sharederrors.CodeUserNotFound, "user not found", err)
		}
		return nil, err
	}
	return u, nil
}

// MarkEmailVerified marks user's email as verified.
func (r *UserRepository) MarkEmailVerified(ctx context.Context, id string) (*domain.User, error) {
	const q = `
UPDATE users
SET email_verified=true, updated_at=NOW()
WHERE id=$1 AND deleted_at IS NULL
RETURNING id, zitadel_user_id, email, email_verified, display_name,
  consent_version, consent_given_at, consent_source,
  created_at, updated_at, deleted_at`

	row := r.client.Pool.QueryRow(ctx, q, id)
	u, err := scanUser(row)
	if err != nil {
		if errors.Is(err, pgx.ErrNoRows) {
			return nil, sharederrors.Wrap(sharederrors.CodeUserNotFound, "user not found", err)
		}
		return nil, err
	}
	return u, nil
}

// SoftDelete marks user as deleted and writes an audit entry.
func (r *UserRepository) SoftDelete(ctx context.Context, id string, actorUserID string) error {
	tx, err := r.client.Pool.Begin(ctx)
	if err != nil {
		return err
	}
	defer func() { _ = tx.Rollback(ctx) }()

	const qDelete = `UPDATE users SET deleted_at=NOW(), updated_at=NOW() WHERE id=$1 AND deleted_at IS NULL`
	res, err := tx.Exec(ctx, qDelete, id)
	if err != nil {
		return err
	}
	if res.RowsAffected() == 0 {
		return sharederrors.Wrap(sharederrors.CodeUserNotFound, "user not found", nil)
	}

	auditID := uuid.NewString()
	const qAudit = `
INSERT INTO user_audit_log (id, actor_user_id, target_user_id, action, metadata_json, created_at)
VALUES ($1,$2,$3,$4,$5,NOW())`
	_, err = tx.Exec(
		ctx,
		qAudit,
		auditID,
		nullIfEmpty(actorUserID),
		id,
		domain.AuditActionGDPRDelete,
		`{"operation":"gdpr_delete"}`,
	)
	if err != nil {
		return err
	}

	if err := tx.Commit(ctx); err != nil {
		return err
	}
	return nil
}

// List returns paginated users.
func (r *UserRepository) List(
	ctx context.Context,
	pagination sharedtypes.Pagination,
	filter domain.ListFilter,
) ([]*domain.User, int64, error) {
	clauses := make([]string, 0)
	args := make([]interface{}, 0)

	if !filter.IncludeDeleted {
		clauses = append(clauses, "deleted_at IS NULL")
	}
	if filter.Email != "" {
		args = append(args, "%"+strings.ToLower(filter.Email)+"%")
		clauses = append(clauses, fmt.Sprintf("LOWER(email) LIKE $%d", len(args)))
	}
	if filter.DisplayName != "" {
		args = append(args, "%"+strings.ToLower(filter.DisplayName)+"%")
		clauses = append(clauses, fmt.Sprintf("LOWER(display_name) LIKE $%d", len(args)))
	}
	if filter.CreatedAfter != nil {
		args = append(args, *filter.CreatedAfter)
		clauses = append(clauses, fmt.Sprintf("created_at >= $%d", len(args)))
	}
	if filter.CreatedBefore != nil {
		args = append(args, *filter.CreatedBefore)
		clauses = append(clauses, fmt.Sprintf("created_at <= $%d", len(args)))
	}

	whereSQL := ""
	if len(clauses) > 0 {
		whereSQL = " WHERE " + strings.Join(clauses, " AND ")
	}

	countQuery := "SELECT COUNT(*) FROM users" + whereSQL
	var total int64
	if err := r.client.Pool.QueryRow(ctx, countQuery, args...).Scan(&total); err != nil {
		return nil, 0, err
	}

	limit := pagination.Limit()
	offset := pagination.Offset()
	args = append(args, limit, offset)
	query := `
SELECT id, zitadel_user_id, email, email_verified, display_name,
  consent_version, consent_given_at, consent_source,
  created_at, updated_at, deleted_at
FROM users` + whereSQL + fmt.Sprintf(" ORDER BY created_at DESC LIMIT $%d OFFSET $%d", len(args)-1, len(args))

	rows, err := r.client.Pool.Query(ctx, query, args...)
	if err != nil {
		return nil, 0, err
	}
	defer rows.Close()

	out := make([]*domain.User, 0)
	for rows.Next() {
		u, err := scanUser(rows)
		if err != nil {
			return nil, 0, err
		}
		out = append(out, u)
	}
	return out, total, rows.Err()
}

// AuditLogsByUserID returns audit entries for a user.
func (r *UserRepository) AuditLogsByUserID(ctx context.Context, id string) ([]domain.AuditLogEntry, error) {
	const q = `
SELECT id, actor_user_id, target_user_id, action, metadata_json::text, created_at
FROM user_audit_log
WHERE target_user_id=$1
ORDER BY created_at DESC`

	rows, err := r.client.Pool.Query(ctx, q, id)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	out := make([]domain.AuditLogEntry, 0)
	for rows.Next() {
		var entry domain.AuditLogEntry
		var actor sql.NullString
		if err := rows.Scan(
			&entry.ID,
			&actor,
			&entry.TargetUserID,
			&entry.Action,
			&entry.MetadataJSON,
			&entry.CreatedAt,
		); err != nil {
			return nil, err
		}
		if actor.Valid {
			entry.ActorUserID = actor.String
		}
		out = append(out, entry)
	}
	return out, rows.Err()
}

// WriteAuditLog writes a custom audit entry.
func (r *UserRepository) WriteAuditLog(ctx context.Context, entry domain.AuditLogEntry) error {
	if entry.ID == "" {
		entry.ID = uuid.NewString()
	}
	if entry.Action == "" {
		entry.Action = "unknown"
	}
	if entry.MetadataJSON == "" {
		entry.MetadataJSON = "{}"
	}
	const q = `
INSERT INTO user_audit_log (id, actor_user_id, target_user_id, action, metadata_json, created_at)
VALUES ($1,$2,$3,$4,$5,NOW())`
	_, err := r.client.Pool.Exec(ctx, q,
		entry.ID,
		nullIfEmpty(entry.ActorUserID),
		entry.TargetUserID,
		entry.Action,
		entry.MetadataJSON,
	)
	return err
}

func nullIfEmpty(v string) interface{} {
	if strings.TrimSpace(v) == "" {
		return nil
	}
	return v
}

func scanUser(scanner interface {
	Scan(dest ...interface{}) error
}) (*domain.User, error) {
	var u domain.User
	var zitadelUserID sql.NullString
	var deletedAt *time.Time
	if err := scanner.Scan(
		&u.ID,
		&zitadelUserID,
		&u.Email,
		&u.EmailVerified,
		&u.DisplayName,
		&u.ConsentVersion,
		&u.ConsentGivenAt,
		&u.ConsentSource,
		&u.CreatedAt,
		&u.UpdatedAt,
		&deletedAt,
	); err != nil {
		return nil, err
	}
	if zitadelUserID.Valid {
		u.ZitadelUserID = zitadelUserID.String
	}
	u.DeletedAt = deletedAt
	return &u, nil
}

func isUniqueViolation(err error) bool {
	if err == nil {
		return false
	}
	return strings.Contains(strings.ToLower(err.Error()), "duplicate key")
}