package themis

import (
	"context"
	"database/sql"
	"embed"
	_ "embed"
	"errors"
	"fmt"
	"strings"

	"github.com/golang-migrate/migrate/v4"
	"github.com/golang-migrate/migrate/v4/database/sqlite3"
	"github.com/golang-migrate/migrate/v4/source/iofs"
	_ "github.com/mattn/go-sqlite3"
	"github.com/rs/zerolog/log"
	"go.opentelemetry.io/otel"
	"go.opentelemetry.io/otel/trace"
)

//go:embed migrations/*.sql
var migrations embed.FS

var tracer trace.Tracer

func init() {
	tp := otel.GetTracerProvider()
	tracer = tp.Tracer("themis")
}

type Store struct {
	db *sql.DB
}

func NewStore(db *sql.DB) (*Store, error) {
	d, err := iofs.New(migrations, "migrations")
	if err != nil {
		return nil, fmt.Errorf("failed to open iofs migration source: %w", err)
	}

	dr, err := sqlite3.WithInstance(db, &sqlite3.Config{})
	if err != nil {
		return nil, fmt.Errorf("failed to initialize sqlite3 migrate driver: %w", err)
	}

	m, err := migrate.NewWithInstance("iofs", d, "main", dr)
	if err != nil {
		return nil, fmt.Errorf("failed to initialize db migrate: %w", err)
	}

	err = m.Up()
	if err != nil && !errors.Is(err, migrate.ErrNoChange) {
		return nil, fmt.Errorf("failed to roll up migrations: %w", err)
	}

	ver, dirty, err := m.Version()
	if err != nil && err != migrate.ErrNilVersion {
		return nil, fmt.Errorf("failed to get database migration version: %w", err)
	}

	log.Debug().Uint("current_version", ver).Bool("dirty", dirty).Msg("running database migrations")

	return &Store{
		db: db,
	}, nil
}

func (s *Store) Close() error {
	log.Debug().Msg("closing database")
	return s.db.Close()
}

func (s *Store) Claim(ctx context.Context, userId, player, province string, claimType ClaimType) (int, error) {
	log.Debug().
		Ctx(ctx).
		Str("userid", userId).
		Str("player", player).
		Str("province", province).
		Stringer("claim_type", claimType).
		Msg("inserting claim")
	audit := &AuditableEvent{
		userId:    userId,
		eventType: EventClaim,
	}
	defer s.Audit(ctx, audit)

	tx, err := s.db.Begin()
	if err != nil {
		audit.err = err
		return 0, fmt.Errorf("failed to begin transaction: %w", err)
	}
	defer tx.Commit() //nolint:errcheck

	conflicts, err := s.FindConflicts(ctx, userId, province, claimType)
	if err != nil {
		audit.err = err
		return 0, fmt.Errorf("failed to run conflicts check: %w", err)
	}

	if len(conflicts) > 0 {
		log.Debug().Ctx(ctx).Int("len", len(conflicts)).Msg("found conflicts")
		audit.err = err
		return 0, ErrConflict{Conflicts: conflicts}
	}

	// check that provided name matches the claim type
	stmt, err := s.db.PrepareContext(ctx, `SELECT COUNT(1) FROM claimables WHERE lower(name) = ? and typ = ?`)
	if err != nil {
		audit.err = err
		return 0, fmt.Errorf("failed to prepare count query: %w", err)
	}
	defer stmt.Close()

	row := stmt.QueryRowContext(ctx, strings.ToLower(province), claimType)
	var count int
	err = row.Scan(&count)
	if err != nil {
		audit.err = err
		return 0, fmt.Errorf("failed to scan: %w", err)
	}

	if count == 0 {
		audit.err = err
		return 0, fmt.Errorf("found no provinces for %s named %s", claimType, province)
	}

	stmt, err = s.db.PrepareContext(ctx, "INSERT INTO claims (player, claim_type, val, userid) VALUES (?, ?, ?, ?)")
	if err != nil {
		audit.err = err
		return 0, fmt.Errorf("failed to prepare claim query: %w", err)
	}
	defer stmt.Close()

	res, err := stmt.ExecContext(ctx, player, claimType, province, userId)
	if err != nil {
		audit.err = err
		return 0, fmt.Errorf("failed to insert claim: %w", err)
	}

	id, err := res.LastInsertId()
	if err != nil {
		audit.err = err
		return 0, fmt.Errorf("failed to get last ID: %w", err)
	}

	return int(id), nil
}

func (s *Store) ListAvailability(ctx context.Context, claimType ClaimType, search ...string) ([]string, error) {
	log.Debug().Ctx(ctx).Stringer("claim_type", claimType).Strs("search_terms", search).Msg("listing available entries")
	queryParams := []any{string(claimType)}

	queryPattern := `SELECT distinct name
	FROM claimables
	LEFT JOIN claims ON claimables.name = claims.val AND claimables.typ = claims.claim_type
	WHERE claims.val IS NULL
	AND claimables.typ = ?`

	if len(search) > 0 && search[0] != "" {
		// only take one search param, ignore the rest
		queryPattern += `AND claimables.name LIKE ?`
		queryParams = append(queryParams, fmt.Sprintf("%%%s%%", search[0]))
	}

	stmt, err := s.db.PrepareContext(ctx, queryPattern)
	if err != nil {
		return nil, fmt.Errorf("failed to prepare query: %w", err)
	}
	defer stmt.Close()

	rows, err := stmt.QueryContext(ctx, queryParams...)
	if err != nil {
		return nil, fmt.Errorf("failed to execute query: %w", err)
	}

	avail := make([]string, 0)
	for rows.Next() {
		var s string
		if err := rows.Scan(&s); err != nil {
			return nil, fmt.Errorf("failed to scan rows: %w", err)
		}
		avail = append(avail, s)
	}

	return avail, nil
}

func (s *Store) ListClaims(ctx context.Context) ([]Claim, error) {
	log.Debug().Ctx(ctx).Msg("listing all claims currently in database")
	stmt, err := s.db.PrepareContext(ctx, `SELECT id, player, claim_type, val FROM claims`)
	if err != nil {
		return nil, fmt.Errorf("failed to prepare query: %w", err)
	}
	defer stmt.Close()

	rows, err := stmt.QueryContext(ctx)
	if err != nil {
		return nil, fmt.Errorf("failed to execute query: %w", err)
	}

	claims := make([]Claim, 0)
	for rows.Next() {
		c := Claim{}
		var rawType string
		err = rows.Scan(&c.ID, &c.Player, &rawType, &c.Name)
		if err != nil {
			return nil, fmt.Errorf("failed to scan row: %w", err)
		}
		cl, err := ClaimTypeFromString(rawType)
		if err != nil {
			return nil, fmt.Errorf("unexpected error converting raw claim type: %w", err)
		}
		c.Type = cl

		claims = append(claims, c)
	}

	return claims, nil
}

type ClaimDetail struct {
	Claim
	Provinces []string
}

func (cd ClaimDetail) String() string {
	sb := strings.Builder{}
	sb.WriteString(fmt.Sprintf("%s\n", cd.Claim))
	for _, p := range cd.Provinces {
		sb.WriteString(fmt.Sprintf("  - %s\n", p))
	}
	return sb.String()
}

func (s *Store) DescribeClaim(ctx context.Context, ID int) (ClaimDetail, error) {
	log.Debug().Ctx(ctx).Int("id", ID).Msg("describing claim")
	stmt, err := s.db.PrepareContext(ctx, `SELECT id, player, claim_type, val FROM claims WHERE id = ?`)
	if err != nil {
		return ClaimDetail{}, fmt.Errorf("failed to get claim: %w", err)
	}
	defer stmt.Close()

	row := stmt.QueryRowContext(ctx, ID)

	c := Claim{}
	var rawType string
	err = row.Scan(&c.ID, &c.Player, &rawType, &c.Name)
	if err == sql.ErrNoRows {
		return ClaimDetail{}, ErrNoSuchClaim
	}
	if err != nil {
		return ClaimDetail{}, fmt.Errorf("failed to scan row: %w", err)
	}
	cl, err := ClaimTypeFromString(rawType)
	if err != nil {
		return ClaimDetail{}, fmt.Errorf("unexpected error converting raw claim type: %w", err)
	}
	c.Type = cl

	stmt, err = s.db.PrepareContext(ctx, `SELECT province FROM claimables WHERE name = ? AND typ = ?`)
	if err != nil {
		return ClaimDetail{}, fmt.Errorf("failed to prepare query: %w", err)
	}
	defer stmt.Close()

	rows, err := stmt.QueryContext(ctx, c.Name, cl)
	if err != nil {
		return ClaimDetail{}, fmt.Errorf("failed to execute query: %w", err)
	}

	provinces := make([]string, 0)
	for rows.Next() {
		var p string
		err = rows.Scan(&p)
		if err != nil {
			return ClaimDetail{}, fmt.Errorf("failed to scan result set: %w", err)
		}
		provinces = append(provinces, p)
	}

	return ClaimDetail{
		Claim:     c,
		Provinces: provinces,
	}, nil
}

func (s *Store) DeleteClaim(ctx context.Context, ID int, userId string) error {
	log.Debug().Ctx(ctx).Str("userid", userId).Int("id", ID).Msg("deleting claim")
	audit := &AuditableEvent{
		userId:    userId,
		eventType: EventUnclaim,
	}
	defer s.Audit(ctx, audit)

	stmt, err := s.db.PrepareContext(ctx, "DELETE FROM claims WHERE id = ? AND userid = ?")
	if err != nil {
		audit.err = err
		return fmt.Errorf("failed to prepare query: %w", err)
	}
	defer stmt.Close()

	res, err := stmt.ExecContext(ctx, ID, userId)
	if err != nil {
		audit.err = err
		return fmt.Errorf("failed to delete claim ID %d: %w", ID, err)
	}

	rows, err := res.RowsAffected()
	if err != nil {
		audit.err = err
		return fmt.Errorf("failed to get affected rows: %w", err)
	}
	if rows == 0 {
		audit.err = ErrNoSuchClaim
		return ErrNoSuchClaim
	}
	return nil
}

func (s *Store) CountClaims(ctx context.Context) (total, uniquePlayers int, err error) {
	log.Debug().Ctx(ctx).Msg("counting all claims and unique users")
	stmt, err := s.db.PrepareContext(ctx, "SELECT COUNT(1), COUNT(DISTINCT(userid)) FROM claims")
	if err != nil {
		return 0, 0, fmt.Errorf("failed to prepare query: %w", err)
	}
	defer stmt.Close()

	res := stmt.QueryRowContext(ctx)

	if err := res.Scan(&total, &uniquePlayers); err != nil {
		return 0, 0, fmt.Errorf("failed to scan result: %w", err)
	}

	return total, uniquePlayers, nil
}

func (s *Store) Flush(ctx context.Context, userId string) error {
	log.Debug().Ctx(ctx).Str("initiated_by", userId).Msg("flushing all currently help claims")
	audit := &AuditableEvent{
		userId:    userId,
		eventType: EventFlush,
	}
	defer s.Audit(ctx, audit)

	_, err := s.db.ExecContext(ctx, "DELETE FROM claims;")
	if err != nil {
		audit.err = err
		return fmt.Errorf("failed to execute delete query: %w", err)
	}
	return nil
}