package distro

import (

	"bufio"

	"encoding/json"

	"errors"

	"fmt"

	"io"

	"os"

	"sort"

	"strings"

	"github.com/osbuild/osbuild-composer/internal/blueprint"

	"github.com/osbuild/osbuild-composer/internal/rpmmd"

)

// A Distro represents composer's notion of what a given distribution is.

type Distro interface {

	// Returns the name of the distro.

	Name() string

	// Returns the module platform id of the distro. This is used by DNF

	// for modularity support.

	ModulePlatformID() string

	// Returns a sorted list of the names of the architectures this distro

	// supports.

	ListArches() []string

	// Returns an object representing the given architecture as support

	// by this distro.

	GetArch(arch string) (Arch, error)

}

// An Arch represents a given distribution's support for a given architecture.

type Arch interface {

	// Returns the name of the architecture.

	Name() string

	// Returns a sorted list of the names of the image types this architecture

	// supports.

	ListImageTypes() []string

	// Returns an object representing a given image format for this architecture,

	// on this distro.

	GetImageType(imageType string) (ImageType, error)

	// Returns the parent distro

	Distro() Distro

}

// An ImageType represents a given distribution's support for a given Image Type

// for a given architecture.

type ImageType interface {

	// Returns the name of the image type.

	Name() string

	// Returns the parent architecture

	Arch() Arch

	// Returns the canonical filename for the image type.

	Filename() string

	// Retrns the MIME-type for the image type.

	MIMEType() string

	// Returns the proper image size for a given output format. If the input size

	// is 0 the default value for the format will be returned.

	Size(size uint64) uint64

	// Returns the default packages to include and exclude when making the image

	// type.

	Packages(bp blueprint.Blueprint) ([]string, []string)

	// Returns the build packages for the output type.

	BuildPackages() []string

	// Returns an osbuild manifest, containing the sources and pipeline necessary

	// to build an image, given output format with all packages and customizations

	// specified in the given blueprint.

	Manifest(b *blueprint.Customizations, options ImageOptions, repos []rpmmd.RepoConfig, packageSpecs, buildPackageSpecs []rpmmd.PackageSpec) (Manifest, error)

}

// The ImageOptions specify options for a specific image build

type ImageOptions struct {

	OSTree OSTreeImageOptions

	Size   uint64

}

// The OSTreeImageOptions specify ostree-specific image options

type OSTreeImageOptions struct {

	Ref    string

	Parent string

}

// A Manifest is an opaque JSON object, which is a valid input to osbuild

type Manifest []byte

func (m Manifest) MarshalJSON() ([]byte, error) {

	return json.RawMessage(m).MarshalJSON()

}

func (m *Manifest) UnmarshalJSON(payload []byte) error {

	var raw json.RawMessage

	err := (&raw).UnmarshalJSON(payload)

	if err != nil {

		return err

	}

	*m = Manifest(raw)

	return nil

}

type Registry struct {

	distros map[string]Distro

}

func NewRegistry(distros ...Distro) (*Registry, error) {

	reg := &Registry{

		distros: make(map[string]Distro),

	}

	for _, distro := range distros {

		name := distro.Name()

		if _, exists := reg.distros[name]; exists {

			return nil, fmt.Errorf("NewRegistry: passed two distros with the same name: %s", distro.Name())

		}

		reg.distros[name] = distro

	}

	return reg, nil

}

func (r *Registry) GetDistro(name string) Distro {

	distro, ok := r.distros[name]

	if !ok {

		return nil

	}

	return distro

}

// List returns the names of all distros in a Registry, sorted alphabetically.

func (r *Registry) List() []string {

	list := []string{}

	for _, distro := range r.distros {

		list = append(list, distro.Name())

	}

	sort.Strings(list)

	return list

}

func (r *Registry) FromHost() (Distro, bool, error) {

	name, beta, err := GetHostDistroName()

	if err != nil {

		return nil, false, err

	}

	d := r.GetDistro(name)

	if d == nil {

		return nil, false, errors.New("unknown distro: " + name)

	}

	return d, beta, nil

}

func GetHostDistroName() (string, bool, error) {

	f, err := os.Open("/etc/os-release")

	if err != nil {

		return "", false, err

	}

	defer f.Close()

	osrelease, err := readOSRelease(f)

	if err != nil {

		return "", false, err

	}

	// NOTE: We only consider major releases

	version := strings.Split(osrelease["VERSION_ID"], ".")

	name := osrelease["ID"] + "-" + version[0]

	// TODO: We should probably index these things by the full CPE

	beta := strings.Contains(osrelease["CPE_NAME"], "beta")

	return name, beta, nil

}

func readOSRelease(r io.Reader) (map[string]string, error) {

	osrelease := make(map[string]string)

	scanner := bufio.NewScanner(r)

	for scanner.Scan() {

		line := strings.TrimSpace(scanner.Text())

		if len(line) == 0 {

			continue

		}

		parts := strings.SplitN(line, "=", 2)

		if len(parts) != 2 {

			return nil, errors.New("readOSRelease: invalid input")

		}

		key := strings.TrimSpace(parts[0])

		value := strings.TrimSpace(parts[1])

		if value[0] == '"' {

			if len(value) < 2 || value[len(value)-1] != '"' {

				return nil, errors.New("readOSRelease: invalid input")

			}

			value = value[1 : len(value)-1]

		}

		osrelease[key] = value

	}

	return osrelease, nil

}