// Copyright (c) 2018-2022, Sylabs Inc. All rights reserved.
// This software is licensed under a 3-clause BSD license. Please consult the
// LICENSE.md file distributed with the sources of this project regarding your
// rights to use or distribute this software.

package sources

import (
	"context"
	"errors"
	"fmt"
	"os"
	"os/exec"
	"path/filepath"
	"regexp"
	"runtime"
	"strings"
	"syscall"

	"github.com/sylabs/singularity/v4/internal/pkg/util/bin"
	"github.com/sylabs/singularity/v4/internal/pkg/util/rpm"
	"github.com/sylabs/singularity/v4/pkg/build/types"
	"github.com/sylabs/singularity/v4/pkg/sylog"
)

const (
	yumConf = "/etc/bootstrap-yum.conf"
)

// YumConveyor holds stuff that needs to be packed into the bundle
type YumConveyor struct {
	b         *types.Bundle
	rpmPath   string
	mirrorurl string
	updateurl string
	osversion string
	include   string
	gpg       string
	setopt    string
}

// YumConveyorPacker only needs to hold the conveyor to have the needed data to pack
type YumConveyorPacker struct {
	YumConveyor
}

// Get downloads container information from the specified source
//
// FIXME: use context for cancellation.
func (c *YumConveyor) Get(_ context.Context, b *types.Bundle) (err error) {
	c.b = b

	// check for dnf or yum on system
	var installCommandPath string
	if installCommandPath, err = bin.FindBin("dnf"); err == nil {
		sylog.Debugf("Found dnf at: %v", installCommandPath)
	} else if installCommandPath, err = bin.FindBin("yum"); err == nil {
		sylog.Debugf("Found yum at: %v", installCommandPath)
	} else {
		return fmt.Errorf("neither yum nor dnf in path")
	}

	// check for rpm on system
	err = c.getRPMPath()
	if err != nil {
		return fmt.Errorf("while checking rpm path: %v", err)
	}

	err = c.getBootstrapOptions()
	if err != nil {
		return fmt.Errorf("while getting bootstrap options: %v", err)
	}

	err = c.genYumConfig()
	if err != nil {
		return fmt.Errorf("while generating yum config: %v", err)
	}

	err = c.makePseudoDevices()
	if err != nil {
		return fmt.Errorf("while copying pseudo devices: %v", err)
	}

	args := []string{`--noplugins`, `-c`, filepath.Join(c.b.RootfsPath, yumConf), `--installroot`, c.b.RootfsPath, `--releasever=` + c.osversion, `-y`}
	if c.setopt != "" {
		args = append(args, "--setopt", c.setopt)
	}
	args = append(args, "install")
	args = append(args, strings.Fields(c.include)...)

	// Do the install
	sylog.Debugf("\n\tInstall Command Path: %s\n\tDetected Arch: %s\n\tOSVersion: %s\n\tMirrorURL: %s\n\tUpdateURL: %s\n\tIncludes: %s\n\tSetopt: %s\n", installCommandPath, runtime.GOARCH, c.osversion, c.mirrorurl, c.updateurl, c.include, c.setopt)
	cmd := exec.Command(installCommandPath, args...)
	if sylog.GetLevel() >= int(sylog.VerboseLevel) {
		cmd.Stdout = os.Stdout
	}
	cmd.Stderr = os.Stderr
	if err = cmd.Run(); err != nil {
		return fmt.Errorf("while bootstrapping: %v", err)
	}

	// clean up bootstrap packages
	os.RemoveAll(filepath.Join(c.b.RootfsPath, "/var/cache/yum-bootstrap"))

	return nil
}

// Pack puts relevant objects in a Bundle!
func (cp *YumConveyorPacker) Pack(context.Context) (b *types.Bundle, err error) {
	err = cp.insertBaseEnv()
	if err != nil {
		return nil, fmt.Errorf("while inserting base environment: %v", err)
	}

	err = cp.insertRunScript()
	if err != nil {
		return nil, fmt.Errorf("while inserting runscript: %v", err)
	}

	return cp.b, nil
}

func (c *YumConveyor) getRPMPath() (err error) {
	c.rpmPath, err = bin.FindBin("rpm")
	if err != nil {
		return fmt.Errorf("rpm is not in path: %v", err)
	}

	// The _db_backednd macro is not defined on EL < 8.
	rpmDBBackend, err := rpm.GetMacro("_db_backend")
	if err != nil && !errors.Is(err, rpm.ErrMacroUndefined) {
		return err
	}
	if rpmDBBackend != "" && rpmDBBackend != "bdb" {
		sylog.Warningf("Your host system is using the %s RPM database backend.", rpmDBBackend)
		sylog.Warningf("Bootstrapping of older distributions that use the bdb backend will fail.")
	}

	rpmDBPath, err := rpm.GetMacro("_dbpath")
	if err != nil {
		return err
	}
	// %{_var}/lib/rpm is the 'traditional' dbpath
	if rpmDBPath != `/var/lib/rpm` {
		// Fedora 36 now uses a different rpm dbpath, and may fail to bootstrap older distros
		if rpmDBPath == `/usr/lib/sysimage/rpm` {
			sylog.Warningf("Your host system is using a new RPM database path: %v", rpmDBPath)
			sylog.Warningf("Bootstrapping of older distributions that use /var/lib/rpm will fail.")
		} else {
			// If we're on a 'foreign' system, with neither old or new paths, and ~/.rpmmacros will be required.
			return fmt.Errorf("RPM database is using a non-standard path: %s\n"+
				"You are probably running this bootstrap on Debian or Ubuntu.\n"+
				"There is a way to work around this problem:\n"+
				"Create a file at path %s/.rpmmacros.\n"+
				"Place the following lines into the '.rpmmacros' file:\n"+
				"%s\n"+
				"%s\n"+
				"After creating the file, re-run the bootstrap.\n",
				rpmDBPath, os.Getenv("HOME"), `%_var /var`, `%_dbpath %{_var}/lib/rpm`)
		}
	}
	return nil
}

func (c *YumConveyor) getBootstrapOptions() (err error) {
	var ok bool

	// look for http_proxy and gpg environment vars
	c.gpg = os.Getenv("GPG")

	// get mirrorURL, updateURL, OSVerison, and Includes components to definition
	c.mirrorurl, ok = c.b.Recipe.Header["mirrorurl"]
	if !ok {
		return fmt.Errorf("invalid yum header, no mirrorurl specified")
	}

	c.updateurl = c.b.Recipe.Header["updateurl"]

	// look for an OS version if a mirror specifies it
	regex := regexp.MustCompile(`(?i)%{OSVERSION}`)
	if regex.MatchString(c.mirrorurl) || regex.MatchString(c.updateurl) {
		c.osversion, ok = c.b.Recipe.Header["osversion"]
		if !ok {
			return fmt.Errorf("invalid yum header, osversion referenced in mirror but no osversion specified")
		}
		c.mirrorurl = regex.ReplaceAllString(c.mirrorurl, c.osversion)
		c.updateurl = regex.ReplaceAllString(c.updateurl, c.osversion)
	}

	include := c.b.Recipe.Header["include"]

	// check for include environment variable and add it to requires string
	include += ` ` + os.Getenv("INCLUDE")

	// trim leading and trailing whitespace
	include = strings.TrimSpace(include)

	// add aa_base to start of include list by default
	include = `/etc/redhat-release coreutils ` + include

	c.include = include

	c.setopt = c.b.Recipe.Header["setopt"]

	return nil
}

func (c *YumConveyor) genYumConfig() (err error) {
	fileContent := "[main]\n"
	fileContent += "cachedir=/var/cache/yum-bootstrap\n"
	fileContent += "keepcache=0\n"
	fileContent += "debuglevel=2\n"
	fileContent += "logfile=/var/log/yum.log\n"
	fileContent += "syslog_device=/dev/null\n"
	fileContent += "exactarch=1\n"
	fileContent += "obsoletes=1\n"
	// gpg
	if c.gpg != "" {
		fileContent += "gpgcheck=1\n"
	} else {
		fileContent += "gpgcheck=0\n"
	}
	fileContent += "plugins=1\n"
	fileContent += "reposdir=0\n"
	fileContent += "deltarpm=0\n"
	fileContent += "\n"
	fileContent += "[base]\n"
	fileContent += "name=Linux $releasever - $basearch\n"
	// mirror
	if c.mirrorurl != "" {
		fileContent += "baseurl=" + c.mirrorurl + "\n"
	}
	fileContent += "enabled=1\n"
	// gpg
	if c.gpg != "" {
		fileContent += "gpgcheck=1\n"
	} else {
		fileContent += "gpgcheck=0\n"
	}

	// add update section if updateurl is specified
	if c.updateurl != "" {
		fileContent += "[updates]\n"
		fileContent += "name=Linux $releasever - $basearch updates\n"
		fileContent += "baseurl=" + c.updateurl + "\n"
		fileContent += "enabled=1\n"
		// gpg
		if c.gpg != "" {
			fileContent += "gpgcheck=1\n"
		} else {
			fileContent += "gpgcheck=0\n"
		}
		fileContent += "\n"
	}

	err = os.Mkdir(filepath.Join(c.b.RootfsPath, "/etc"), 0o775)
	if err != nil {
		return fmt.Errorf("while creating %v: %v", filepath.Join(c.b.RootfsPath, "/etc"), err)
	}

	err = os.WriteFile(filepath.Join(c.b.RootfsPath, yumConf), []byte(fileContent), 0o664)
	if err != nil {
		return fmt.Errorf("while creating %v: %v", filepath.Join(c.b.RootfsPath, yumConf), err)
	}

	// if gpg key is specified, import it
	if c.gpg != "" {
		err = c.importGPGKey()
		if err != nil {
			return fmt.Errorf("while importing gpg key: %v", err)
		}
	} else {
		sylog.Infof("Skipping GPG Key Import")
	}

	return nil
}

func (c *YumConveyor) importGPGKey() (err error) {
	sylog.Infof("We have a GPG key!  Preparing RPM database.")

	// make sure gpg is being imported over https
	if !strings.HasPrefix(c.gpg, "https://") {
		return fmt.Errorf("gpg key must be fetched with https")
	}

	// make sure curl is installed so rpm can import gpg key
	if _, err = bin.FindBin("curl"); err != nil {
		return fmt.Errorf("neither yum nor dnf in path")
	}

	cmd := exec.Command(c.rpmPath, "--root", c.b.RootfsPath, "--initdb")
	cmd.Stdout = os.Stdout
	cmd.Stderr = os.Stderr
	if err = cmd.Run(); err != nil {
		return fmt.Errorf("while initializing new rpm db: %v", err)
	}

	cmd = exec.Command(c.rpmPath, "--root", c.b.RootfsPath, "--import", c.gpg)
	cmd.Stdout = os.Stdout
	cmd.Stderr = os.Stderr
	if err = cmd.Run(); err != nil {
		return fmt.Errorf("while importing gpg key with rpm: %v", err)
	}

	sylog.Infof("GPG key import complete!")

	return nil
}

//nolint:dupl
func (c *YumConveyor) makePseudoDevices() (err error) {
	devPath := filepath.Join(c.b.RootfsPath, "dev")
	err = os.Mkdir(devPath, 0o775)
	if err != nil {
		return fmt.Errorf("while creating %v: %v", devPath, err)
	}

	devs := []struct {
		major int
		minor int
		path  string
		mode  uint32
	}{
		{1, 3, "/dev/null", syscall.S_IFCHR | 0o666},
		{1, 8, "/dev/random", syscall.S_IFCHR | 0o666},
		{1, 9, "/dev/urandom", syscall.S_IFCHR | 0o666},
		{1, 5, "/dev/zero", syscall.S_IFCHR | 0o666},
	}

	for _, dev := range devs {
		d := int((dev.major << 8) | (dev.minor & 0xff) | ((dev.minor & 0xfff00) << 12))
		path := filepath.Join(c.b.RootfsPath, dev.path)

		if err := syscall.Mknod(path, dev.mode, d); err != nil {
			return fmt.Errorf("while creating %s: %s", path, err)
		}
	}

	return nil
}

func (cp *YumConveyorPacker) insertBaseEnv() (err error) {
	if err = makeBaseEnv(cp.b.RootfsPath); err != nil {
		return
	}
	return nil
}

func (cp *YumConveyorPacker) insertRunScript() (err error) {
	err = os.WriteFile(filepath.Join(cp.b.RootfsPath, "/.singularity.d/runscript"), []byte("#!/bin/sh\n"), 0o755)
	if err != nil {
		return
	}

	return nil
}