package domain

import (
	"errors"
	"time"
)

var (
	ErrPrerequisiteNotMet      = errors.New("prerequisites not completed")
	ErrProgressNotFound        = errors.New("progress record not found")
	ErrPrerequisiteExists      = errors.New("prerequisite already exists")
	ErrSelfPrerequisite        = errors.New("sub-course cannot be its own prerequisite")
	ErrSubCourseAlreadyStarted = errors.New("sub-course already started")
)

type SubCoursePrerequisite struct {
	ID                       int64
	SubCourseID              int64
	PrerequisiteSubCourseID  int64
	PrerequisiteTitle        string
	PrerequisiteLevel        string
	PrerequisiteDisplayOrder int32
	CreatedAt                time.Time
}

type SubCourseDependent struct {
	ID                      int64
	SubCourseID             int64
	PrerequisiteSubCourseID int64
	DependentTitle          string
	DependentLevel          string
	CreatedAt               time.Time
}

type ProgressStatus string

const (
	ProgressStatusNotStarted ProgressStatus = "NOT_STARTED"
	ProgressStatusInProgress ProgressStatus = "IN_PROGRESS"
	ProgressStatusCompleted  ProgressStatus = "COMPLETED"
)

type UserSubCourseProgress struct {
	ID                 int64
	UserID             int64
	SubCourseID        int64
	Status             ProgressStatus
	ProgressPercentage int16
	StartedAt          *time.Time
	CompletedAt        *time.Time
	CreatedAt          time.Time
	UpdatedAt          *time.Time
}

type SubCourseWithProgress struct {
	SubCourseID             int64
	Title                   string
	Description             *string
	Thumbnail               *string
	DisplayOrder            int32
	Level                   string
	IsActive                bool
	ProgressStatus          ProgressStatus
	ProgressPercentage      int16
	StartedAt               *time.Time
	CompletedAt             *time.Time
	UnmetPrerequisitesCount int64
	IsLocked                bool
}

type UserCourseProgressItem struct {
	ID                    int64
	UserID                int64
	SubCourseID           int64
	Status                ProgressStatus
	ProgressPercentage    int16
	StartedAt             *time.Time
	CompletedAt           *time.Time
	CreatedAt             time.Time
	UpdatedAt             *time.Time
	SubCourseTitle        string
	SubCourseLevel        string
	SubCourseDisplayOrder int32
}