package themis

import (
	"context"
	"fmt"

	"github.com/rs/zerolog/log"
	"go.opentelemetry.io/otel/attribute"
	"go.opentelemetry.io/otel/codes"
	semconv "go.opentelemetry.io/otel/semconv/v1.24.0"
	"go.opentelemetry.io/otel/trace"
)

type Conflict struct {
	Province  string
	Player    string
	ClaimType ClaimType
	Claim     string
	ClaimID   int
}

func (c Conflict) String() string {
	return fmt.Sprintf("%s owned by #%d %s %s (%s)", c.Province, c.ClaimID, c.ClaimType, c.Claim, c.Player)
}

const conflictQuery string = `WITH claiming AS (
  SELECT province FROM claimables
  WHERE claimables.typ = ?
  AND claimables.name = ?
)
SELECT claimables.province, claims.player, claims.claim_type, claims.val, claims.id
FROM claims
INNER JOIN claimables
  ON claims.claim_type = claimables.typ
  AND claims.val = claimables.name
INNER JOIN claiming
  ON claiming.province = claimables.province
WHERE claims.userid  IS NOT ?;`

func (s *Store) FindConflicts(ctx context.Context, userId, name string, claimType ClaimType) ([]Conflict, error) {
	ctx, span := tracer.Start(ctx, "find_conflicts", trace.WithAttributes(
		semconv.DBSystemSqlite,
		semconv.DBSQLTable("claims"),
		semconv.DBOperation("select"),
		attribute.String("user_id", userId),
		attribute.String("claim_name", name),
		attribute.Stringer("claim_type", claimType),
	))
	defer span.End()

	log.Debug().Ctx(ctx).Stringer("claim_type", claimType).Str("userid", userId).Msg("searching for potential conflicts")

	stmt, err := s.db.PrepareContext(ctx, conflictQuery)
	if err != nil {
		span.RecordError(err)
		span.SetStatus(codes.Error, "failed to prepare query")
		return nil, fmt.Errorf("failed to prepare conflicts query: %w", err)
	}

	rows, err := stmt.QueryContext(ctx, claimType, name, userId)
	if err != nil {
		span.RecordError(err)
		span.SetStatus(codes.Error, "failed to execute query")
		return nil, fmt.Errorf("failed to get conflicting provinces: %w", err)
	}
	defer stmt.Close()

	conflicts := make([]Conflict, 0)
	for rows.Next() {
		var (
			province   string
			player     string
			sClaimType string
			claimName  string
			claimId    int
		)
		err = rows.Scan(&province, &player, &sClaimType, &claimName, &claimId)
		if err != nil {
			span.RecordError(err)
			span.SetStatus(codes.Error, "failed to scan row")
			return nil, fmt.Errorf("failed to scan row: %w", err)
		}

		ct, err := ClaimTypeFromString(sClaimType)
		if err != nil {
			// In case of an error parsing the claim type, simply default to
			// whatever the database sends; this is a read-only function, the
			// input validation is assumed to have already been done at insert.
			ct = ClaimType(sClaimType)
		}
		conflicts = append(conflicts, Conflict{
			Province:  province,
			Player:    player,
			ClaimType: ct,
			Claim:     claimName,
			ClaimID:   claimId,
		})
	}

	return conflicts, nil
}