package store

import (
	"context"
	"database/sql"
	"fmt"
	"time"
)

// DurableAssignment is the persistence form of a verified assignment-ready
// projection. It deliberately keeps player ownership in the primary key and
// query predicate so another participant cannot recover its join material.
type DurableAssignment struct {
	MatchID           string
	PlayerID          string
	AllocationID      string
	ServerID          string
	Slot              int
	Region            string
	ClientBuild       string
	ProtocolVersion   int
	Transport         string
	Endpoint          string
	JoinAuthorisation string
	ManifestDigest    []byte
	ExpiresAt         time.Time
	Revision          uint64
}

const AssignmentUpsertSQL = `INSERT INTO assignments
    (match_id, player_id, allocation_id, server_id, slot, region, client_build,
     protocol_version, transport, endpoint, join_authorisation, manifest_digest,
     expires_at, revision)
VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12, $13, $14)
ON CONFLICT (match_id, player_id) DO UPDATE SET
    allocation_id = EXCLUDED.allocation_id, server_id = EXCLUDED.server_id,
    slot = EXCLUDED.slot, region = EXCLUDED.region, client_build = EXCLUDED.client_build,
    protocol_version = EXCLUDED.protocol_version, transport = EXCLUDED.transport,
    endpoint = EXCLUDED.endpoint, join_authorisation = EXCLUDED.join_authorisation,
    manifest_digest = EXCLUDED.manifest_digest, expires_at = EXCLUDED.expires_at,
    revision = EXCLUDED.revision
WHERE assignments.allocation_id = EXCLUDED.allocation_id
  AND assignments.server_id = EXCLUDED.server_id
  AND assignments.slot = EXCLUDED.slot
  AND assignments.region = EXCLUDED.region
  AND assignments.client_build = EXCLUDED.client_build
  AND assignments.protocol_version = EXCLUDED.protocol_version
  AND assignments.transport = EXCLUDED.transport
  AND assignments.endpoint = EXCLUDED.endpoint
  AND assignments.join_authorisation = EXCLUDED.join_authorisation
  AND assignments.manifest_digest = EXCLUDED.manifest_digest
  AND assignments.expires_at = EXCLUDED.expires_at
  AND assignments.revision = EXCLUDED.revision`

const AssignmentSelectSQL = `SELECT match_id, player_id, allocation_id, server_id,
    slot, region, client_build, protocol_version, transport, endpoint,
    join_authorisation, manifest_digest, expires_at, revision
FROM assignments
WHERE match_id = $1 AND player_id = $2 AND expires_at > $3`

func validateDurableAssignment(assignment DurableAssignment) error {
	if assignment.MatchID == "" || assignment.PlayerID == "" || assignment.AllocationID == "" || assignment.ServerID == "" || assignment.Slot < 0 || assignment.Slot > 5 || (assignment.Region != "EU" && assignment.Region != "NA") || assignment.ClientBuild == "" || assignment.ProtocolVersion < 1 || (assignment.Transport != "enet" && assignment.Transport != "steam_sdr") || assignment.Endpoint == "" || assignment.JoinAuthorisation == "" || len(assignment.ManifestDigest) == 0 || assignment.ExpiresAt.IsZero() || assignment.Revision < 0 {
		return fmt.Errorf("invalid durable assignment")
	}
	return nil
}

func SaveAssignment(ctx context.Context, db *sql.DB, assignment DurableAssignment) error {
	if db == nil {
		return fmt.Errorf("invalid assignment database")
	}
	if err := validateDurableAssignment(assignment); err != nil {
		return err
	}
	result, err := db.ExecContext(ctx, AssignmentUpsertSQL, assignment.MatchID, assignment.PlayerID, assignment.AllocationID, assignment.ServerID, assignment.Slot, assignment.Region, assignment.ClientBuild, assignment.ProtocolVersion, assignment.Transport, assignment.Endpoint, assignment.JoinAuthorisation, assignment.ManifestDigest, assignment.ExpiresAt, assignment.Revision)
	if err != nil {
		return err
	}
	changed, err := result.RowsAffected()
	if err != nil {
		return err
	}
	if changed != 1 {
		return fmt.Errorf("assignment persistence conflict")
	}
	return nil
}

func GetAssignment(ctx context.Context, db *sql.DB, playerID, matchID string, now time.Time) (DurableAssignment, error) {
	if db == nil || playerID == "" || matchID == "" || now.IsZero() {
		return DurableAssignment{}, fmt.Errorf("invalid assignment recovery arguments")
	}
	var assignment DurableAssignment
	err := db.QueryRowContext(ctx, AssignmentSelectSQL, matchID, playerID, now).Scan(&assignment.MatchID, &assignment.PlayerID, &assignment.AllocationID, &assignment.ServerID, &assignment.Slot, &assignment.Region, &assignment.ClientBuild, &assignment.ProtocolVersion, &assignment.Transport, &assignment.Endpoint, &assignment.JoinAuthorisation, &assignment.ManifestDigest, &assignment.ExpiresAt, &assignment.Revision)
	if err != nil {
		return DurableAssignment{}, err
	}
	if err := validateDurableAssignment(assignment); err != nil {
		return DurableAssignment{}, err
	}
	return assignment, nil
}