package model

import (
	"context"
	"errors"
	"time"

	"github.com/jinzhu/gorm"
	errs "github.com/pkg/errors"
)

var (
	ErrMissingWorkgroup                = errs.New("missing workgroup")
	ErrInvalidWorkgroup                = errs.New("invalid workgroup")
	ErrDecisionSupportFileDoesNotExist = errs.New("decision support file does not exist")
)

type DSFRepository struct {
	db *gorm.DB
}

func (r *DSFRepository) Create(ctx context.Context, changes *DecisionSupportFileChanges) (*DecisionSupportFile, error) {
	dsf := &DecisionSupportFile{}

	if err := r.updateFromChanges(dsf, changes); err != nil {
		return nil, errs.WithStack(err)
	}

	if err := r.db.Save(&dsf).Error; err != nil {
		return nil, errs.WithStack(err)
	}

	return dsf, nil
}

func (r *DSFRepository) Update(ctx context.Context, id string, changes *DecisionSupportFileChanges) (*DecisionSupportFile, error) {
	dsf := &DecisionSupportFile{}

	if err := r.db.Find(dsf, "id = ?", id).Error; err != nil {
		return nil, errs.WithStack(err)
	}

	if err := r.updateFromChanges(dsf, changes); err != nil {
		return nil, errs.WithStack(err)
	}

	if err := r.db.Save(dsf).Error; err != nil {
		return nil, errs.WithStack(err)
	}

	return dsf, nil
}

func (r *DSFRepository) updateFromChanges(dsf *DecisionSupportFile, changes *DecisionSupportFileChanges) error {
	if changes.WorkgroupID == nil {
		return errs.WithStack(ErrMissingWorkgroup)
	}

	wg := &Workgroup{}
	if err := r.db.Model(wg).First(wg, "id = ?", changes.WorkgroupID).Error; err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return errs.WithStack(ErrInvalidWorkgroup)
		}

		return errs.WithStack(err)
	}

	dsf.Workgroup = wg

	if changes.Sections != nil {
		dsf.Sections = changes.Sections
	}

	if changes.Title != nil {
		dsf.Title = *changes.Title
	}

	if changes.Status != nil {
		if dsf.Status != StatusVoted && *changes.Status == StatusVoted {
			dsf.VotedAt = time.Now().UTC()
		}

		if *changes.Status == StatusClosed {
			dsf.VotedAt = time.Time{}
		}

		dsf.Status = *changes.Status
	}

	return nil
}

func (r *DSFRepository) Find(ctx context.Context, id string) (*DecisionSupportFile, error) {
	dsf := &DecisionSupportFile{}
	query := r.db.Model(dsf).Preload("Workgroup").Where("id = ?", id)

	if err := query.First(&dsf).Error; err != nil {
		return nil, errs.WithStack(err)
	}

	return dsf, nil
}

func (r *DSFRepository) Search(ctx context.Context, filter *DecisionSupportFileFilter) ([]*DecisionSupportFile, error) {
	query := r.db.Model(&DecisionSupportFile{}).Preload("Workgroup")

	if filter != nil {
		if filter.Ids != nil {
			query = query.Where("id in (?)", filter.Ids)
		}
	}

	dsfs := make([]*DecisionSupportFile, 0)

	if err := query.Find(&dsfs).Error; err != nil {
		return nil, errs.WithStack(err)
	}

	return dsfs, nil
}

func NewDSFRepository(db *gorm.DB) *DSFRepository {
	return &DSFRepository{db}
}