package spitfire

import (
	"crypto/sha1"
	"fmt"
	"io"
	"log"
	"os"
	"strings"
	"time"
)

// Package the APPINDEX update process
func PackageAPPINDEX(name, release, version, arch, size, installedSize, description, url, license, origin, maintainer, dependencies, platform string) error {
	// Mock package file name
	pkgFile := fmt.Sprintf("%s-%s", name, version)

	// Calculate checksums
	checksum := calcChecksum(pkgFile)
	contentChecksum := calcChecksum(pkgFile)

	// Timestamp
	timestamp := time.Now().Unix()

	// Remove existing entry based on P, R, A, and o fields
	removeExistingEntry(name, release, arch, origin)

	// Open or create the APPINDEX file for appending
	file, err := os.OpenFile("./APPINDEX", os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
	if err != nil {
		log.Fatalf("Failed to open APPINDEX file: %v", err)
	}
	defer file.Close()

	// Write the new entry
	entry := fmt.Sprintf(`
C:%s
P:%s
R:%s
V:%s
A:%s
S:%s
I:%s
T:%s
U:%s
L:%s
o:%s
m:%s
t:%d
c:%s
D:%s
p:%s
q:
Z:%s

`, checksum, name, release, version, arch, size, installedSize, description, url, license, origin, maintainer, timestamp, contentChecksum, dependencies, platform, checksum)

	if _, err := file.WriteString(entry); err != nil {
		log.Fatalf("Failed to write to APPINDEX file: %v", err)
	}

	fmt.Println("APPINDEX has been updated successfully.")
	return nil
}

// calcChecksum calculates a checksum (SHA-1) for a given input string
func calcChecksum(input string) string {
	h := sha1.New()
	_, _ = io.WriteString(h, input)
	return fmt.Sprintf("%x", h.Sum(nil))
}

// removeExistingEntry removes an existing entry from APPINDEX based on P, R, A, and o fields
func removeExistingEntry(name, release, arch, origin string) {
	// Read file contents
	content, err := os.ReadFile("./APPINDEX")
	if err != nil {
		if os.IsNotExist(err) {
			return // If file does not exist, no need to remove anything
		}
		log.Fatalf("Failed to read APPINDEX: %v", err)
	}

	// Remove lines matching the package with the same P, R, A, and o fields
	lines := strings.Split(string(content), "\n")
	var newLines []string
	remove := false
	for _, line := range lines {
		// Detect start of an entry by matching on P, R, A, and o
		if strings.HasPrefix(line, "P:"+name) {
			remove = true
		}
		if remove && strings.HasPrefix(line, "R:"+release) {
			remove = true
		}
		if remove && strings.HasPrefix(line, "A:"+arch) {
			remove = true
		}
		if remove && strings.HasPrefix(line, "o:"+origin) {
			remove = true
		}

		// Stop removal at the end of an entry
		if remove && line == "" {
			remove = false
			continue // Skip the line
		}

		// Append lines that are not part of the matching entry
		if !remove {
			newLines = append(newLines, line)
		}
	}

	// Write the updated contents back to the file
	err = os.WriteFile("./APPINDEX", []byte(strings.Join(newLines, "\n")), 0644)
	if err != nil {
		log.Fatalf("Failed to update APPINDEX: %v", err)
	}
}

// CleanAppIndex cleans up any orphaned "C:" entries and collapses excessive newlines
func CleanAppIndex() error {
	// Read file contents
	content, err := os.ReadFile("./APPINDEX")
	if err != nil {
		return fmt.Errorf("failed to read APPINDEX: %v", err)
	}

	// Split the file content into lines
	lines := strings.Split(string(content), "\n")
	var newLines []string
	var currentEntry []string
	inEntry := false

	for _, line := range lines {
		line = strings.TrimSpace(line)

		// Start of an entry when we encounter a checksum
		if strings.HasPrefix(line, "C:") {
			// If we already have a valid entry, add it to newLines
			if inEntry && len(currentEntry) > 1 {
				newLines = append(newLines, currentEntry...)
			}
			currentEntry = []string{line}
			inEntry = true
		} else if inEntry && line == "" {
			// End of an entry
			if len(currentEntry) > 1 {
				newLines = append(newLines, currentEntry...)
				newLines = append(newLines, "") // Add a blank line to separate entries
			}
			currentEntry = nil
			inEntry = false
		} else if inEntry {
			// Continue adding lines to the current entry
			currentEntry = append(currentEntry, line)
		} else if line != "" {
			// Add non-entry lines (for extra safety)
			newLines = append(newLines, line)
		}
	}

	// In case the last entry was valid
	if inEntry && len(currentEntry) > 1 {
		newLines = append(newLines, currentEntry...)
	}

	// Collapse consecutive blank lines
	cleanedContent := strings.Join(newLines, "\n")
	cleanedContent = strings.ReplaceAll(cleanedContent, "\n\n\n", "\n\n")

	// Write the cleaned content back to the file
	err = os.WriteFile("./APPINDEX", []byte(cleanedContent), 0644)
	if err != nil {
		return fmt.Errorf("failed to write cleaned APPINDEX: %v", err)
	}

	fmt.Println("APPINDEX cleaned successfully.")
	return nil
}