package services

import (
	"context"
	"errors"
	"git.aiterp.net/stufflog/server/database/repositories"
	"git.aiterp.net/stufflog/server/graph/loaders"
	"git.aiterp.net/stufflog/server/internal/generate"
	"git.aiterp.net/stufflog/server/internal/slerrors"
	"git.aiterp.net/stufflog/server/models"
	"github.com/gin-gonic/gin"
	"math/rand"
	"time"
)

var ErrLoginFailed = errors.New("login failed")
var ErrInternalLoginFailure = errors.New("login failed due to internal error")
var ErrInternalPermissionFailure = errors.New("permission check failed due to internal error")
var ErrWrongCurrentPassword = errors.New("current password is missing")
var ErrMissingCurrentPassword = errors.New("current password is missing")

var authCookieName = "stufflog_cookie"
var authCtxKey = "stufflog.auth"
var ginCtxKey = "stufflog.gin"

type Auth struct {
	users    repositories.UserRepository
	session  repositories.SessionRepository
	projects repositories.ProjectRepository
	issues   repositories.IssueRepository
}

func (auth *Auth) Login(ctx context.Context, username, password string) (*models.User, error) {
	user, err := auth.users.Find(ctx, username)
	if err != nil {
		select {
		case <-time.After(time.Millisecond * time.Duration(rand.Int63n(100)+100)):
		case <-ctx.Done():
		}
		return nil, ErrLoginFailed
	}

	if !user.CheckPassword(password) {
		select {
		case <-time.After(time.Millisecond * time.Duration(rand.Int63n(50))):
		case <-ctx.Done():
		}
		return nil, ErrLoginFailed
	}

	session := models.Session{
		ID:         generate.SessionID(),
		UserID:     user.ID,
		ExpiryTime: time.Now().Add(time.Hour * 168),
	}
	err = auth.session.Save(ctx, session)
	if err != nil {
		return nil, ErrInternalLoginFailure
	}

	if c := ctx.Value(ginCtxKey).(*gin.Context); c != nil {
		c.SetCookie(authCookieName, session.ID, 3600*168, "/", "", false, true)
	} else {
		return nil, ErrInternalLoginFailure
	}

	return user, nil
}

func (auth *Auth) Logout(ctx context.Context) (*models.User, error) {
	user := auth.UserFromContext(ctx)
	if user == nil {
		return nil, slerrors.PermissionDenied
	}

	c, ok := ctx.Value(ginCtxKey).(*gin.Context)
	if !ok {
		return nil, ErrInternalLoginFailure
	}

	c.SetCookie(authCookieName, "", 0, "/", "", false, true)

	return user, nil
}

func (auth *Auth) CreateUser(ctx context.Context, username, password, name string, active, admin bool) (*models.User, error) {
	loggedInUser := auth.UserFromContext(ctx)
	if loggedInUser == nil || !loggedInUser.Admin {
		return nil, slerrors.PermissionDenied
	}

	user := &models.User{
		ID:     username,
		Name:   name,
		Active: active,
		Admin:  admin,
	}
	err := user.SetPassword(password)
	if err != nil {
		return nil, err
	}

	user, err = auth.users.Insert(ctx, *user)
	if err != nil {
		return nil, err
	}

	return user, nil
}

func (auth *Auth) UserFromContext(ctx context.Context) *models.User {
	user, _ := ctx.Value(authCtxKey).(*models.User)
	return user
}

func (auth *Auth) ProjectPermission(ctx context.Context, projectID string) (*models.ProjectPermission, error) {
	user := auth.UserFromContext(ctx)
	if user == nil || !user.Active {
		return nil, slerrors.PermissionDenied
	}

	permission, err := loaders.ProjectPermissionLoaderFromContext(ctx).Load(projectID)
	if err != nil {
		return nil, ErrInternalPermissionFailure
	}
	if permission.Level == models.ProjectPermissionLevelNoAccess {
		return nil, slerrors.PermissionDenied
	}

	return permission, nil
}

func (auth *Auth) IssuePermission(ctx context.Context, issue models.Issue) (*models.ProjectPermission, error) {
	user := auth.UserFromContext(ctx)
	if user == nil || !user.Active {
		return nil, slerrors.PermissionDenied
	}

	isOwnedOrAssigned := issue.AssigneeID == user.ID || issue.OwnerID == user.ID

	permission, err := loaders.ProjectPermissionLoaderFromContext(ctx).Load(issue.ProjectID)
	if err != nil {
		return nil, ErrInternalPermissionFailure
	}
	if permission.Level == models.ProjectPermissionLevelNoAccess {
		return nil, slerrors.PermissionDenied
	}
	if !(permission.CanViewAnyIssue() || (permission.CanViewOwnIssue() && isOwnedOrAssigned)) {
		return nil, slerrors.PermissionDenied
	}

	return permission, nil
}

func (auth *Auth) CheckGinSession(c *gin.Context) {
	ctx := context.WithValue(c.Request.Context(), ginCtxKey, c)

	cookie, err := c.Cookie(authCookieName)
	if err != nil {
		c.Request = c.Request.WithContext(ctx)
		return
	}

	session, err := auth.session.Find(c.Request.Context(), cookie)
	if err != nil {
		c.Request = c.Request.WithContext(ctx)
		return
	}

	if time.Until(session.ExpiryTime) < time.Hour*167 {
		session.ExpiryTime = time.Now().Add(time.Hour * 168)
		_ = auth.session.Save(c.Request.Context(), *session)
		c.SetCookie(authCookieName, session.ID, 3600*168, "/", "", false, true)
	}

	user, err := auth.users.Find(c.Request.Context(), session.UserID)
	if err != nil {
		c.Request = c.Request.WithContext(ctx)
		return
	}

	ctx = context.WithValue(ctx, authCtxKey, user)
	c.Request = c.Request.WithContext(ctx)
}

func (auth *Auth) EditUser(ctx context.Context, username string, setName *string, currentPassword *string, newPassword *string) (*models.User, error) {
	loggedInUser := auth.UserFromContext(ctx)
	if loggedInUser == nil {
		return nil, slerrors.PermissionDenied
	}

	user, err := auth.users.Find(ctx, username)
	if err != nil {
		return nil, err
	}

	if user.ID != loggedInUser.ID && !loggedInUser.Admin {
		return nil, slerrors.PermissionDenied
	}

	if newPassword != nil {
		// Only require current password if it's given, or if the user is NOT an admin changing
		// another user's password
		if currentPassword != nil || !(loggedInUser.Admin && loggedInUser.ID != user.ID) {
			if currentPassword == nil {
				return nil, ErrMissingCurrentPassword
			}
			if !user.CheckPassword(*currentPassword) {
				return nil, ErrWrongCurrentPassword
			}
		}

		err = user.SetPassword(*newPassword)
		if err != nil {
			return nil, err
		}
	}

	if setName != nil && *setName != "" {
		user.Name = *setName
	}

	err = auth.users.Save(ctx, *user)
	if err != nil {
		return nil, err
	}

	return user, nil
}

func (auth *Auth) FilterLogListCopy(ctx context.Context, logs []*models.Log) []*models.Log {
	logs2 := make([]*models.Log, 0, len(logs))
	for _, log := range logs {
		logs2 = append(logs2, log.Copy())
	}

	auth.FilterLogList(ctx, &logs2)

	return logs2
}

func (auth *Auth) FilterLogList(ctx context.Context, logs *[]*models.Log) {
	user := auth.UserFromContext(ctx)
	if user == nil {
		panic("Auth.FilterLogList called without user")
	}

	auth.FilterLog(ctx, *logs...)
	deleteList := make([]int, 0, len(*logs)/2)
	for i, log := range *logs {
		if log.Empty() && log.UserID != user.ID {
			deleteList = append(deleteList, i-len(deleteList))
		}
	}

	list := *logs
	for _, index := range deleteList {
		list = append(list[:index], list[index+1:]...)
	}
	*logs = list
}

func (auth *Auth) FilterLog(ctx context.Context, logs ...*models.Log) {
	userID := ""
	if user := auth.UserFromContext(ctx); user != nil {
		userID = user.ID
	}

	accessMap := make(map[string]bool)
	deleteList := make([]int, 0, 16)
	for _, log := range logs {
		if userID == log.UserID {
			continue
		}

		deleteList = deleteList[:0]
		for i, item := range log.Items {
			if access, ok := accessMap[item.IssueID]; ok && access {
				continue
			} else if ok && !access {
				deleteList = append(deleteList, i-len(deleteList))
				continue
			}

			issue, err := loaders.IssueLoaderFromContext(ctx).Load(item.IssueID)
			if err != nil {
				deleteList = append(deleteList, i-len(deleteList))
				accessMap[item.IssueID] = true
				continue
			}

			_, err = auth.IssuePermission(ctx, *issue)
			if err != nil {
				deleteList = append(deleteList, i-len(deleteList))
			}

			accessMap[issue.ID] = err != nil
		}
		for _, index := range deleteList {
			log.Items = append(log.Items[:index], log.Items[index+1:]...)
		}
		deleteList = deleteList[:0]
		for i, task := range log.Tasks {
			if access, ok := accessMap[task.IssueID]; ok && access {
				continue
			} else if ok && !access {
				deleteList = append(deleteList, i-len(deleteList))
				continue
			}

			issue, err := loaders.IssueLoaderFromContext(ctx).Load(task.IssueID)
			if err != nil {
				deleteList = append(deleteList, i-len(deleteList))
				accessMap[task.IssueID] = true
				continue
			}

			_, err = auth.IssuePermission(ctx, *issue)
			if err != nil {
				deleteList = append(deleteList, i-len(deleteList))
			}

			accessMap[issue.ID] = err != nil
		}
		for _, index := range deleteList {
			log.Tasks = append(log.Tasks[:index], log.Tasks[index+1:]...)
		}
	}
}