package distros

import (
	"fmt"
	"net/url"
	"strings"

	"libguestfs.org/guestfs"
)

func debianCommandToUpdatePackageCache() []string {
	return []string{"sudo", "apt", "update"}
}

func (mgr *TemplateManager) replaceDebianMirrorUrl(handle *guestfs.Guestfs, uri string) (string, error) {
	parsedUrl, err := url.Parse(uri)
	if err != nil {
		return "", fmt.Errorf("Could not parse URL '%s': %w", uri, err)
	}
	// See https://manpages.debian.org/stable/apt/sources.list.5.en.html#URI_SPECIFICATION
	// There are many more URI types, but these are the ones which I've seen so far in the
	// official Debian cloud images
	if parsedUrl.Scheme == "http" || parsedUrl.Scheme == "https" {
		parsedUrl.Host = mgr.cfg.MirrorHost
		return parsedUrl.String(), nil
	} else if parsedUrl.Scheme == "mirror+file" {
		// The file is a mirrorlist
		filePath := uri[len("mirror+file://"):]
		content, err := handle.Cat(filePath)
		if err != nil {
			return "", fmt.Errorf("Could not read %s: %w", filePath, err)
		}
		oldLines := strings.Split(content, "\n")
		newLines := []string{}
		for _, oldLine := range oldLines {
			if oldLine == "" || strings.HasPrefix(oldLine, "#") {
				newLines = append(newLines, oldLine)
				continue
			}
			parsedUrl, err := url.Parse(oldLine)
			if err != nil {
				return "", fmt.Errorf("Could not parse URL in %s: '%s'", filePath, oldLine)
			}
			if parsedUrl.Scheme != "http" && parsedUrl.Scheme != "https" {
				return "", fmt.Errorf("Unexpected URL scheme in %s: '%s'", filePath, oldLine)
			}
			parsedUrl.Host = mgr.cfg.MirrorHost
			newLine := parsedUrl.String()
			mgr.logger.Debug().
				Str("file", filePath).
				Str("oldURL", oldLine).
				Str("newURL", newLine).
				Msg("Replacing URL")
			newLines = append(newLines, newLine)
		}
		newContent := strings.Join(newLines, "\n")
		err = handle.Write(filePath, []byte(newContent))
		if err != nil {
			return "", fmt.Errorf("Error writing to %s: %w", filePath, err)
		}
		// Original URL (mirror+file://) does not change
		return uri, nil
	} else {
		return "", fmt.Errorf("Unexpected scheme in URL: %s", uri)
	}
}

// See https://manpages.debian.org/stable/apt/sources.list.5.en.html#ONE-LINE-STYLE_FORMAT
func (mgr *TemplateManager) replaceDebianMirrorUrls_OneLineStyle(handle *guestfs.Guestfs, filePath string) error {
	log := mgr.logger
	// Some Augeas nodes under /files/etc/apt/sources.list are comments,
	// so we use /*/uri to make sure that we only get the actual entries
	sourcesListEntries, err := handle.Aug_match("/files" + filePath + "/*/uri")
	if err != nil {
		return err
	}
	for _, uriPath := range sourcesListEntries {
		var (
			oldURL    string
			newURL    string
			typeValue string
			distValue string
		)
		if oldURL, err = handle.Aug_get(uriPath); err != nil {
			return err
		}
		newURL, err = mgr.replaceDebianMirrorUrl(handle, oldURL)
		if err != nil {
			return err
		}
		// strip off the "/uri" from the node path
		entryPath := uriPath[:len(uriPath)-4]
		typePath := entryPath + "/type"
		if typeValue, err = handle.Aug_get(typePath); err != nil {
			return err
		}
		distPath := entryPath + "/distribution"
		if distValue, err = handle.Aug_get(distPath); err != nil {
			return err
		}
		if typeValue == "deb-src" {
			log.Debug().
				Str("URL", oldURL).
				Str("distribution", distValue).
				Msg("Removing deb-src entry")
			if _, err = handle.Aug_rm(entryPath); err != nil {
				return err
			}
			continue
		}
		if oldURL == newURL {
			continue
		}
		log.Debug().
			Str("distribution", distValue).
			Str("oldURL", oldURL).
			Str("newURL", newURL).
			Str("file", filePath).
			Msg("Replacing URL")
		if err = handle.Aug_set(uriPath, newURL); err != nil {
			return err
		}
	}
	return nil
}

// See https://manpages.debian.org/stable/apt/sources.list.5.en.html#DEB822-STYLE_FORMAT
func (mgr *TemplateManager) replaceDebianMirrorUrls_Deb822Style(handle *guestfs.Guestfs, filePath string) error {
	// Augeas doesn't support this style unfortunately, so we're going to
	// have to parse the file manually
	content, err := handle.Cat(filePath)
	if err != nil {
		return fmt.Errorf("Could not read %s: %w", filePath, err)
	}
	oldLines := strings.Split(content, "\n")
	newLines := []string{}
	for _, oldLine := range oldLines {
		if strings.HasPrefix(oldLine, "Types:") {
			oldTypes := strings.Split(
				strings.TrimLeft(oldLine[len("Types:"):], " "),
				" ",
			)
			if len(oldTypes) == 0 || len(oldTypes) > 2 {
				return fmt.Errorf(
					"Could not determine Debian archive types from this line in %s: '%s'",
					filePath, oldLine,
				)
			}
			if oldTypes[0] == "deb-src" || (len(oldTypes) == 2 && oldTypes[1] == "deb-src") {
				mgr.logger.Debug().Str("file", filePath).Msg("Removing deb-src type")
			}
			newLines = append(newLines, "Types: deb")
		} else if strings.HasPrefix(oldLine, "URIs:") {
			oldURL := strings.TrimLeft(oldLine[len("URIs:"):], " ")
			newURL, err := mgr.replaceDebianMirrorUrl(handle, oldURL)
			if err != nil {
				return err
			}
			if oldURL != newURL {
				mgr.logger.Debug().
					Str("file", filePath).
					Str("oldURL", oldURL).
					Str("newURL", newURL).
					Msg("Replacing URL")
			}
			newLines = append(newLines, "URIs: "+newURL)
		} else {
			newLines = append(newLines, oldLine)
		}
	}
	newContent := strings.Join(newLines, "\n")
	err = handle.Write(filePath, []byte(newContent))
	if err != nil {
		return fmt.Errorf("Error writing to %s: %w", filePath, err)
	}
	return nil
}

func (mgr *TemplateManager) replaceDebianMirrorUrls(handle *guestfs.Guestfs) error {
	filePaths := []string{"/etc/apt/sources.list"}
	extraSourceDirPath := "/etc/apt/sources.list.d"
	extraSourceDirExists, err := handle.Is_dir(extraSourceDirPath, nil)
	if err != nil {
		return fmt.Errorf("Could not determine if %s is a directory: %w", extraSourceDirPath, err)
	}
	if extraSourceDirExists {
		extraSourceFiles, err := handle.Ls(extraSourceDirPath)
		if err != nil {
			return fmt.Errorf("Could not list files in %s: %w", extraSourceDirPath, err)
		}
		for _, filename := range extraSourceFiles {
			filePaths = append(filePaths, extraSourceDirPath+"/"+filename)
		}
	}
	for _, filePath := range filePaths {
		if strings.HasSuffix(filePath, ".list") {
			err = mgr.replaceDebianMirrorUrls_OneLineStyle(handle, filePath)
		} else if strings.HasSuffix(filePath, ".sources") {
			err = mgr.replaceDebianMirrorUrls_Deb822Style(handle, filePath)
		} else {
			err = fmt.Errorf("Could not determine type of Debian source file %s", filePath)
		}
		if err != nil {
			return err
		}
	}
	return nil
}