package onboarding

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"time"

	"github.com/jackc/pgx/v5"
	"github.com/jackc/pgx/v5/pgxpool"
)

type StateStore struct {
	Pool *pgxpool.Pool
}

func (s StateStore) Load(ctx context.Context) (State, error) {
	if s.Pool == nil {
		return State{}, errors.New("onboarding state store is not configured")
	}
	var raw []byte
	if err := s.Pool.QueryRow(ctx, `SELECT value FROM system_settings WHERE key=$1`, StateKey).Scan(&raw); err != nil {
		if errors.Is(err, pgx.ErrNoRows) {
			return State{SchemaVersion: SchemaVersion, Step: "welcome"}, nil
		}
		return State{}, fmt.Errorf("load onboarding state: %w", err)
	}
	var state State
	if err := json.Unmarshal(raw, &state); err != nil {
		return State{}, fmt.Errorf("decode onboarding state: %w", err)
	}
	if state.SchemaVersion != SchemaVersion {
		return State{}, fmt.Errorf("unsupported onboarding state schema version %d", state.SchemaVersion)
	}
	return state, nil
}

func (s StateStore) Save(ctx context.Context, state State) error {
	if s.Pool == nil {
		return errors.New("onboarding state store is not configured")
	}
	state.SchemaVersion = SchemaVersion
	state.UpdatedAt = time.Now().UTC()
	raw, err := json.Marshal(state)
	if err != nil {
		return fmt.Errorf("encode onboarding state: %w", err)
	}
	if _, err := s.Pool.Exec(ctx, `INSERT INTO system_settings (key,value,version) VALUES ($1,$2::jsonb,1) ON CONFLICT (key) DO UPDATE SET value=EXCLUDED.value,version=system_settings.version+1,updated_at=now()`, StateKey, raw); err != nil {
		return fmt.Errorf("save onboarding state: %w", err)
	}
	return nil
}