package meta

import (
	"encoding/json"
	"errors"
	"fmt"
	"os"
	"strings"

	"github.com/adrg/xdg"
)

type Meta struct {
	Packages []Package `json:"packages"`
}

type Package struct {
	Name    string `json:"name"`
	Version string `json:"version"`
}

func Add(pkg Package) error {
	m, err := Read()
	if err != nil {
		return err
	}
	for _, p := range m.Packages {
		if strings.EqualFold(pkg.Name, p.Name) {
			return errors.New("package already exists locally")
		}
	}
	m.Packages = append(m.Packages, pkg)
	return save(m)
}

func Read() (Meta, error) {
	var m Meta
	fp, err := metaPath()
	if err != nil {
		return m, fmt.Errorf("could not get meta file: %w", err)
	}
	fi, err := os.Open(fp)
	if err != nil {
		return m, fmt.Errorf("could not open meta file: %w", err)
	}
	defer fi.Close()

	if err := json.NewDecoder(fi).Decode(&m); err != nil {
		return m, fmt.Errorf("could not decode meta: %w", err)
	}
	return m, nil
}

func Remove(name string) error {
	m, err := Read()
	if err != nil {
		return err
	}
	for idx, p := range m.Packages {
		if strings.EqualFold(name, p.Name) {
			m.Packages = append(m.Packages[:idx], m.Packages[idx+1:]...)
			return save(m)
		}
	}
	return fmt.Errorf("could not find package to remove for %q", name)
}

func metaPath() (string, error) {
	return xdg.DataFile("eget/meta.json")
}

func save(m Meta) error {
	fp, err := metaPath()
	if err != nil {
		return fmt.Errorf("could not get meta path: %w", err)
	}
	fi, err := os.Create(fp)
	if err != nil {
		return fmt.Errorf("could not create meta file: %w", err)
	}
	defer fi.Close()
	return json.NewEncoder(fi).Encode(m)
}