package projecttxt

import (
	"bufio"
	"errors"
	"fmt"
	"io/ioutil"
	"os"
	"strings"
)

type ProjectList struct {
	Projects []*Project `json:"projects"`
}

func NewProjectList() *ProjectList                           { return &ProjectList{Projects: []*Project{}} }
func (projectlist *ProjectList) Size() int                   { return len(projectlist.Projects) }
func (projectlist *ProjectList) GetProjectSlice() []*Project { return projectlist.Projects }

func (projectlist *ProjectList) GetProjectsWithContext(context string) *ProjectList {
	return projectlist.Filter(func(p *Project) bool {
		return p.HasContext(context)
	})
}

func (projectlist *ProjectList) GetProjectsWithProjectTag(projectTag string) *ProjectList {
	return projectlist.Filter(func(p *Project) bool {
		return p.HasProjectTag(projectTag)
	})
}

// Filter filters the current TimerList for the given predicate (a function that takes a timer as input and returns a
// bool), and returns a new ProjectList. The original ProjectList is not modified.
func (projectlist *ProjectList) Filter(predicate func(*Project) bool) *ProjectList {
	var newList ProjectList
	for _, t := range projectlist.Projects {
		if predicate(t) {
			newList.AddProject(t)
		}
	}
	return &newList
}

func (projectlist *ProjectList) GetNextId() int {
	nextId := 0
	for _, p := range projectlist.Projects {
		if p.Id > nextId {
			nextId = p.Id
		}
	}
	return nextId + 1
}

// AddProject prepends a Project to the current ProjectList and takes care to set the ProjectId correctly
func (projectlist *ProjectList) AddProject(project *Project) {
	project.Id = projectlist.GetNextId()
	projectlist.Projects = append(projectlist.Projects, project)
}

// AddProjects adds all passed projects to the list
func (projectlist *ProjectList) AddProjects(projects []*Project) {
	for _, v := range projects {
		projectlist.AddProject(v)
	}
}
func (projectlist *ProjectList) Combine(other *ProjectList) { projectlist.AddProjects(other.Projects) }

// GetProject returns the Project with the given project 'id' form the ProjectList.
// Returns an error if Project could not be found.
func (projectlist *ProjectList) GetProject(id int) (*Project, error) {
	for i := range projectlist.Projects {
		if projectlist.Projects[i].Id == id {
			return projectlist.Projects[i], nil
		}
	}
	return nil, errors.New("project not found")
}

// RemoveProjectById removes any Project with given Project 'id' from the ProjectList.
// Returns an error if no Project was removed.
func (projectlist *ProjectList) RemoveProjectById(id int) error {
	found := false
	var remIdx int
	var p *Project
	for remIdx, p = range projectlist.Projects {
		if p.Id == id {
			found = true
			break
		}
	}
	if !found {
		return errors.New("project not found")
	}
	projectlist.Projects = append(projectlist.Projects[:remIdx], projectlist.Projects[remIdx+1:]...)
	return nil
}

// RemoveProject removes any Project from the ProjectList with the same String representation as the given Project.
// Returns an error if no Project was removed.
func (projectlist *ProjectList) RemoveProject(project Project) error {
	found := false
	var remIdx int
	var p *Project
	for remIdx, p = range projectlist.Projects {
		if p.String() == project.String() {
			found = true
			break
		}
	}
	if !found {
		return errors.New("project not found")
	}
	projectlist.Projects = append(projectlist.Projects[:remIdx], projectlist.Projects[remIdx+1:]...)
	return nil
}

// ArchiveProjctToFile removes the project from the active list and concatenates it to
// the passed in filename
// Return an err if any part of that fails
func (projectlist *ProjectList) ArchiveProjectToFile(project Project, filename string) error {
	if err := projectlist.RemoveProject(project); err != nil {
		return err
	}
	f, err := os.OpenFile(filename, os.O_APPEND|os.O_WRONLY, 0600)
	if err != nil {
		return err
	}
	defer f.Close()
	_, err = f.WriteString(project.String() + "\n")
	return err
}

func (projectlist *ProjectList) ResetIds() {
	projectId := 1
	for _, v := range projectlist.Projects {
		v.Id = projectId
		projectId++
	}
}

// LoadFromFile loads a ProjectList from *os.File.
// Note: This will clear the current TimerList and overwrite it's contents with whatever is in *os.File.
func (projectlist *ProjectList) LoadFromFile(file *os.File) error {
	projectlist.Projects = []*Project{} // Empty projectlist
	projectId := 1
	scanner := bufio.NewScanner(file)
	for scanner.Scan() {
		text := strings.Trim(scanner.Text(), "\t\n\r") // Read Line
		// Ignore blank lines
		if text == "" {
			continue
		}
		project, err := ParseProject(text)
		if err != nil {
			return err
		}
		project.Id = projectId
		projectId++
		projectlist.Projects = append(projectlist.Projects, project)
	}
	if err := scanner.Err(); err != nil {
		return err
	}
	return nil
}

// WriteToFile writes a ProjectList to *os.File
func (projectlist *ProjectList) WriteToFile(file *os.File) error {
	writer := bufio.NewWriter(file)
	_, err := writer.WriteString(projectlist.String())
	writer.Flush()
	if err != nil {
		return err
	}
	projectlist.ResetIds()
	return nil
}

// LoadFromFilename loads a ProjectList from the filename.
func (projectlist *ProjectList) LoadFromFilename(filename string) error {
	file, err := os.Open(filename)
	if err != nil {
		return err
	}
	defer file.Close()
	return projectlist.LoadFromFile(file)
}

// WriteToFilename writes a ProjectList to the specified file (most likely called "project.txt").
func (projectlist *ProjectList) WriteToFilename(filename string) error {
	if err := ioutil.WriteFile(filename, []byte(projectlist.String()), 0640); err != nil {
		return err
	}
	projectlist.ResetIds()
	return nil
}

// String returns a complete list of projects in project.txt format.
func (projectlist ProjectList) String() string {
	var ret string
	for _, project := range projectlist.Projects {
		ret += fmt.Sprintf("%s\n", project.String())
	}
	return ret
}

// LoadFromFile loads and returns a ProjectList from *os.File.
func LoadFromFile(file *os.File) (*ProjectList, error) {
	projectlist := ProjectList{}
	if err := projectlist.LoadFromFile(file); err != nil {
		return nil, err
	}
	return &projectlist, nil
}

// WriteToFile writes a ProjectList to *os.File.
func WriteToFile(projectlist *ProjectList, file *os.File) error {
	return projectlist.WriteToFile(file)
}

// LoadFromFilename loads and returns a ProjectList from a file (most likely called "project.txt")
func LoadFromFilename(filename string) (*ProjectList, error) {
	projectlist := ProjectList{}
	if err := projectlist.LoadFromFilename(filename); err != nil {
		return nil, err
	}
	return &projectlist, nil
}

// WriteToFilename write a ProjectList to the specified file (most likely called "project.txt")
func WriteToFilename(projectlist *ProjectList, filename string) error {
	return projectlist.WriteToFilename(filename)
}