package store

import (
	"context"
	"database/sql"
	"encoding/json"
	"errors"
	"fmt"

	"github.com/google/uuid"
	"github.com/jmoiron/sqlx"

	"git.hangman-lab.top/hzhang/Dialectic.Backend/internal/models"
)

type SignupStore struct {
	db *sqlx.DB
}

func NewSignupStore(db *sqlx.DB) *SignupStore { return &SignupStore{db: db} }

type UpsertSignupInput struct {
	TopicID      string
	AgentID      string
	WillingCamps []models.Camp
	PreValidated bool
}

// Upsert creates or updates an agent's signup for a topic. Re-signup
// replaces willing_camps (intentional: lets an agent change their mind
// before signup_close_at).
func (s *SignupStore) Upsert(ctx context.Context, in UpsertSignupInput) (*models.SignupView, error) {
	if len(in.WillingCamps) == 0 {
		return nil, fmt.Errorf("willing_camps must be non-empty")
	}
	for _, c := range in.WillingCamps {
		if !models.IsCampValid(c) {
			return nil, fmt.Errorf("invalid camp %q", c)
		}
	}
	raw, err := json.Marshal(in.WillingCamps)
	if err != nil {
		return nil, err
	}

	// Try insert; on duplicate (topic, agent), update.
	id := uuid.NewString()
	_, err = s.db.ExecContext(ctx, `
		INSERT INTO signups (id, topic_id, agent_id, willing_camps, pre_validated)
		VALUES (?, ?, ?, ?, ?)
		ON DUPLICATE KEY UPDATE
		  willing_camps = VALUES(willing_camps),
		  pre_validated = VALUES(pre_validated)`,
		id, in.TopicID, in.AgentID, raw, in.PreValidated)
	if err != nil {
		return nil, fmt.Errorf("upsert signup: %w", err)
	}
	return s.GetByPair(ctx, in.TopicID, in.AgentID)
}

func (s *SignupStore) GetByPair(ctx context.Context, topicID, agentID string) (*models.SignupView, error) {
	var row models.Signup
	err := s.db.GetContext(ctx, &row,
		`SELECT * FROM signups WHERE topic_id = ? AND agent_id = ?`, topicID, agentID)
	if errors.Is(err, sql.ErrNoRows) {
		return nil, ErrNotFound
	}
	if err != nil {
		return nil, err
	}
	v, err := row.View()
	if err != nil {
		return nil, err
	}
	return &v, nil
}

// ListByTopic returns all signups for a topic. Used by the allocation
// algorithm at signup_close_at and by the topic-detail UI.
func (s *SignupStore) ListByTopic(ctx context.Context, topicID string) ([]models.SignupView, error) {
	var rows []models.Signup
	if err := s.db.SelectContext(ctx, &rows,
		`SELECT * FROM signups WHERE topic_id = ? ORDER BY created_at ASC`, topicID); err != nil {
		return nil, err
	}
	out := make([]models.SignupView, 0, len(rows))
	for _, r := range rows {
		v, err := r.View()
		if err != nil {
			return nil, err
		}
		out = append(out, v)
	}
	return out, nil
}