package showcase

import (
	"bufio"
	"fmt"
	"math/rand"
	"os"
	"path/filepath"
	"strings"
	"time"
)

func init() {
	rand.Seed(time.Now().UnixNano())
}

// extractCodeSnippet extracts a random code snippet from the repository
func extractCodeSnippet(repoPath string, languages []LanguageStats) (string, string, error) {
	if len(languages) == 0 {
		return "", "", fmt.Errorf("no programming languages found")
	}

	// Get the primary language (highest percentage)
	primaryLang := languages[0].Name

	// Define file extensions for each language
	langExtensions := map[string][]string{
		"Go":         {".go"},
		"Python":     {".py"},
		"JavaScript": {".js"},
		"TypeScript": {".ts"},
		"Java":       {".java"},
		"C":          {".c", ".h"},
		"C++":        {".cpp", ".cc", ".cxx", ".hpp"},
		"C/C++":      {".h"},
		"C#":         {".cs"},
		"Ruby":       {".rb"},
		"PHP":        {".php"},
		"Swift":      {".swift"},
		"Kotlin":     {".kt"},
		"Rust":       {".rs"},
		"Shell":      {".sh", ".bash"},
		"Perl":       {".pl", ".pm"},
		"Raku":       {".raku", ".rakumod", ".p6", ".pm6"},
		"Haskell":    {".hs"},
		"Lua":        {".lua"},
		"HTML":       {".html", ".htm"},
		"CSS":        {".css"},
		"SQL":        {".sql"},
		"Make":       {"Makefile", "makefile", "GNUmakefile"},
		"HCL":        {".tf", ".tfvars", ".hcl"},
		"AWK":        {".awk", ".cgi"}, // .cgi files can be AWK scripts
	}

	// Get file extensions for the primary language
	extensions, ok := langExtensions[primaryLang]
	if !ok {
		// Try other languages if primary doesn't have extensions defined
		for _, lang := range languages {
			if exts, exists := langExtensions[lang.Name]; exists {
				extensions = exts
				primaryLang = lang.Name
				break
			}
		}
		if len(extensions) == 0 {
			return "", "", fmt.Errorf("no known file extensions for languages")
		}
	}

	// Find all files matching the extensions
	var codeFiles []string
	err := filepath.Walk(repoPath, func(path string, info os.FileInfo, err error) error {
		if err != nil {
			return nil
		}

		// Skip directories
		if info.IsDir() {
			name := info.Name()
			// Skip hidden directories and common non-code directories
			if strings.HasPrefix(name, ".") && name != "." ||
				name == "node_modules" ||
				name == "vendor" ||
				name == "target" ||
				name == "dist" ||
				name == "build" ||
				name == "__pycache__" {
				return filepath.SkipDir
			}
			return nil
		}

		// Skip files that are too large
		if info.Size() > 1*1024*1024 { // 1MB
			return nil
		}

		// Check if file matches extensions
		basename := filepath.Base(path)
		ext := filepath.Ext(path)

		matched := false
		for _, validExt := range extensions {
			if validExt == basename || (strings.HasPrefix(validExt, ".") && ext == validExt) {
				matched = true
				break
			}
		}

		// For executable files, also check shebang if primary language is AWK and file has .cgi extension
		if !matched && primaryLang == "AWK" && ext == ".cgi" && info.Mode()&0111 != 0 {
			if file, err := os.Open(path); err == nil {
				scanner := bufio.NewScanner(file)
				if scanner.Scan() {
					firstLine := scanner.Text()
					if strings.Contains(firstLine, "awk") || strings.Contains(firstLine, "gawk") {
						matched = true
					}
				}
				file.Close()
			}
		}

		if matched {
			// Skip test files and generated files
			if !strings.Contains(basename, "_test") &&
				!strings.Contains(basename, ".test.") &&
				!strings.Contains(basename, ".min.") &&
				!strings.Contains(path, "/test/") &&
				!strings.Contains(path, "/tests/") {
				codeFiles = append(codeFiles, path)
			}
		}

		return nil
	})

	if err != nil {
		return "", "", err
	}

	if len(codeFiles) == 0 {
		return "", "", fmt.Errorf("no code files found")
	}

	// Try multiple files to find one with good line lengths
	rand.Shuffle(len(codeFiles), func(i, j int) {
		codeFiles[i], codeFiles[j] = codeFiles[j], codeFiles[i]
	})

	var snippet string
	var selectedFile string

	// Try up to 5 files to find a good snippet
	for i := 0; i < len(codeFiles) && i < 5; i++ {
		candidateFile := codeFiles[i]
		candidateSnippet, err := extractSnippetFromFile(candidateFile, 10, 15)
		if err != nil {
			continue
		}

		// Check if this snippet has acceptable line lengths
		if hasAcceptableLineLength(candidateSnippet, 80) {
			snippet = candidateSnippet
			selectedFile = candidateFile
			break
		}

		// Keep the first valid snippet as fallback
		if snippet == "" {
			snippet = candidateSnippet
			selectedFile = candidateFile
		}
	}

	if snippet == "" {
		return "", "", fmt.Errorf("no valid code snippets found")
	}

	// Get relative path for display
	relPath, _ := filepath.Rel(repoPath, selectedFile)

	return snippet, fmt.Sprintf("%s from `%s`", primaryLang, relPath), nil
}

// extractSnippetFromFile extracts a code snippet from a file
func extractSnippetFromFile(filePath string, minLines, maxLines int) (string, error) {
	file, err := os.Open(filePath)
	if err != nil {
		return "", err
	}
	defer file.Close()

	// Read all lines
	var lines []string
	scanner := bufio.NewScanner(file)
	for scanner.Scan() {
		lines = append(lines, scanner.Text())
	}

	if err := scanner.Err(); err != nil {
		return "", err
	}

	totalLines := len(lines)
	if totalLines == 0 {
		return "", fmt.Errorf("file is empty")
	}

	// Try to find the smallest complete function
	bestFunction := findSmallestCompleteFunction(lines)
	if bestFunction != "" {
		return stripComments(bestFunction), nil
	}

	// If no complete function found, try to find a complete function/method
	functionStart, functionEnd := findCompleteFunctionOrMethod(lines, minLines, maxLines*2) // Allow larger functions
	if functionStart >= 0 && functionEnd >= 0 {
		snippet := strings.Join(lines[functionStart:functionEnd+1], "\n")
		return stripComments(snippet), nil
	}

	// Fallback to finding an interesting start with at least minLines
	interestingStart := findInterestingStart(lines, minLines)
	if interestingStart >= 0 {
		endLine := interestingStart + minLines
		if endLine > totalLines {
			endLine = totalLines
		}
		snippet := strings.Join(lines[interestingStart:endLine], "\n")
		return stripComments(snippet), nil
	}

	// Last resort: return first minLines (skip imports if possible)
	skipLines := 0
	for i, line := range lines {
		trimmed := strings.TrimSpace(line)
		if trimmed != "" && !strings.HasPrefix(trimmed, "import") &&
			!strings.HasPrefix(trimmed, "package") && !strings.HasPrefix(trimmed, "using") &&
			!strings.HasPrefix(trimmed, "#include") && !strings.HasPrefix(trimmed, "from") {
			skipLines = i
			break
		}
	}

	endLine := skipLines + minLines
	if endLine > totalLines {
		endLine = totalLines
	}

	snippet := strings.Join(lines[skipLines:endLine], "\n")
	return stripComments(snippet), nil
}

// findSmallestCompleteFunction finds the smallest complete function in the file
func findSmallestCompleteFunction(lines []string) string {
	type functionInfo struct {
		start int
		end   int
		size  int
	}

	var functions []functionInfo

	// Keywords that typically start functions/methods
	functionKeywords := []string{
		"func ", "function ", "def ", "public ", "private ", "protected ",
		"static ", "async ", "procedure ", "sub ", "method ",
	}

	// Find all complete functions
	for i := 0; i < len(lines); i++ {
		line := strings.TrimSpace(lines[i])

		// Check if this line starts a function
		isFunction := false
		for _, keyword := range functionKeywords {
			if strings.Contains(line, keyword) && !strings.HasPrefix(line, "//") && !strings.HasPrefix(line, "#") {
				isFunction = true
				break
			}
		}

		if !isFunction {
			continue
		}

		// Try to find the end of this function
		functionEnd := findFunctionEnd(lines, i)
		if functionEnd > i {
			size := functionEnd - i + 1
			// Only consider functions between 5 and 50 lines
			if size >= 5 && size <= 50 {
				functions = append(functions, functionInfo{
					start: i,
					end:   functionEnd,
					size:  size,
				})
			}
		}
	}

	// Find the smallest function with acceptable line lengths
	if len(functions) > 0 {
		// First try to find a function with all lines <= 80 chars
		for _, f := range functions {
			snippet := strings.Join(lines[f.start:f.end+1], "\n")
			if hasAcceptableLineLength(snippet, 80) {
				return snippet
			}
		}

		// If none found, return the smallest function (will be broken later)
		smallest := functions[0]
		for _, f := range functions[1:] {
			if f.size < smallest.size {
				smallest = f
			}
		}
		return strings.Join(lines[smallest.start:smallest.end+1], "\n")
	}

	return ""
}

// findFunctionEnd finds the end of a function starting at the given line
func findFunctionEnd(lines []string, start int) int {
	if start >= len(lines) {
		return -1
	}

	// For brace-based languages
	braceCount := 0
	inFunction := false

	// For Python - track initial indentation
	isPython := strings.Contains(lines[start], "def ") || strings.Contains(lines[start], "class ")
	var initialIndent int
	if isPython && start < len(lines)-1 {
		// Get indentation of first line after def
		for i := start + 1; i < len(lines); i++ {
			if strings.TrimSpace(lines[i]) != "" {
				initialIndent = len(lines[i]) - len(strings.TrimLeft(lines[i], " \t"))
				break
			}
		}
	}

	for i := start; i < len(lines); i++ {
		line := lines[i]
		trimmed := strings.TrimSpace(line)

		// Handle Python indentation
		if isPython && i > start {
			if trimmed == "" {
				continue
			}
			currentIndent := len(line) - len(strings.TrimLeft(line, " \t"))
			if currentIndent < initialIndent {
				return i - 1
			}
		}

		// Handle brace-based languages
		for _, ch := range line {
			if ch == '{' {
				braceCount++
				inFunction = true
			} else if ch == '}' {
				braceCount--
				if braceCount == 0 && inFunction {
					return i
				}
			}
		}
	}

	// If we're in Python and reached the end, return the last line
	if isPython {
		return len(lines) - 1
	}

	return -1
}

// findCompleteFunctionOrMethod finds a complete function or method within size constraints
func findCompleteFunctionOrMethod(lines []string, minLines, maxLines int) (int, int) {
	// Keywords that typically start functions/methods
	functionKeywords := []string{
		"func ", "function ", "def ", "public ", "private ", "protected ",
		"static ", "async ", "procedure ", "sub ", "method ",
	}

	// Try to find a function that fits within our size constraints
	for i := 0; i < len(lines); i++ {
		line := strings.TrimSpace(lines[i])

		// Check if this line starts a function
		isFunction := false
		for _, keyword := range functionKeywords {
			if strings.Contains(line, keyword) && !strings.HasPrefix(line, "//") && !strings.HasPrefix(line, "#") {
				isFunction = true
				break
			}
		}

		if !isFunction {
			continue
		}

		// Try to find the end of this function
		functionEnd := findFunctionEnd(lines, i)
		if functionEnd > i {
			functionLength := functionEnd - i + 1
			if functionLength >= minLines && functionLength <= maxLines {
				return i, functionEnd
			}
		}
	}

	return -1, -1
}

// findInterestingStart tries to find a good starting point for the snippet
func findInterestingStart(lines []string, snippetSize int) int {
	// Look for function/class definitions
	keywords := []string{
		"func ", "function ", "def ", "class ", "public class",
		"interface ", "struct ", "type ", "const ", "var ",
		"procedure ", "sub ", "method ",
	}

	for i := 0; i < len(lines)-snippetSize; i++ {
		line := strings.TrimSpace(lines[i])
		// Skip empty lines and comments
		if line == "" || strings.HasPrefix(line, "//") || strings.HasPrefix(line, "#") ||
			strings.HasPrefix(line, "/*") || strings.HasPrefix(line, "*") {
			continue
		}

		// Check for interesting keywords
		for _, keyword := range keywords {
			if strings.Contains(line, keyword) {
				// Found something interesting, start here
				return i
			}
		}
	}

	// No interesting start found
	return -1
}

// stripComments removes comment lines from code snippets to make them more concise
func stripComments(code string) string {
	lines := strings.Split(code, "\n")
	var result []string
	inMultilineComment := false

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

		// Handle multi-line comments for C-style languages
		if strings.Contains(line, "/*") {
			inMultilineComment = true
			// If comment ends on same line, process the rest
			if strings.Contains(line, "*/") {
				inMultilineComment = false
				// Skip this line entirely if it's just a comment
				if strings.TrimSpace(strings.Split(line, "/*")[0]) == "" {
					continue
				}
			} else {
				continue
			}
		}

		if inMultilineComment {
			if strings.Contains(line, "*/") {
				inMultilineComment = false
			}
			continue
		}

		// Skip single-line comments
		if trimmed == "" {
			// Keep empty lines for readability
			result = append(result, line)
		} else if strings.HasPrefix(trimmed, "//") ||
			strings.HasPrefix(trimmed, "#") && !strings.HasPrefix(trimmed, "#include") && !strings.HasPrefix(trimmed, "#define") ||
			strings.HasPrefix(trimmed, "<!--") ||
			strings.HasPrefix(trimmed, "*") && len(trimmed) > 1 && trimmed[1] == ' ' {
			// Skip comment lines
			continue
		} else if strings.HasPrefix(trimmed, "\"\"\"") || strings.HasPrefix(trimmed, "'''") {
			// Skip Python docstrings (simplified - doesn't handle all cases)
			continue
		} else {
			// Keep the line but remove inline comments for some languages
			// This is a simple approach - doesn't handle all edge cases
			if idx := strings.Index(line, " //"); idx > 0 {
				// Check if it's not inside a string (very basic check)
				beforeComment := line[:idx]
				if strings.Count(beforeComment, "\"")%2 == 0 && strings.Count(beforeComment, "'")%2 == 0 {
					line = strings.TrimRight(line[:idx], " \t")
				}
			}
			result = append(result, line)
		}
	}

	// Remove leading and trailing empty lines
	for len(result) > 0 && strings.TrimSpace(result[0]) == "" {
		result = result[1:]
	}
	for len(result) > 0 && strings.TrimSpace(result[len(result)-1]) == "" {
		result = result[:len(result)-1]
	}

	// Remove unnecessary indentation
	result = removeCommonIndentation(result)

	// Break long lines
	result = breakLongLines(result, 80)

	return strings.Join(result, "\n")
}

// removeCommonIndentation removes common leading whitespace from all lines
func removeCommonIndentation(lines []string) []string {
	if len(lines) == 0 {
		return lines
	}

	// Find the common prefix of whitespace
	var commonPrefix string
	firstNonEmpty := -1

	// Find first non-empty line to use as reference
	for i, line := range lines {
		if strings.TrimSpace(line) != "" {
			firstNonEmpty = i
			break
		}
	}

	if firstNonEmpty == -1 {
		return lines
	}

	// Get the whitespace prefix of the first non-empty line
	firstLine := lines[firstNonEmpty]
	for i, ch := range firstLine {
		if ch != ' ' && ch != '\t' {
			commonPrefix = firstLine[:i]
			break
		}
	}

	// If the first line has no indentation, return as-is
	if commonPrefix == "" {
		return lines
	}

	// Find the actual common prefix among all non-empty lines
	for _, line := range lines {
		if strings.TrimSpace(line) == "" {
			continue
		}

		// Reduce commonPrefix to what this line shares
		for i := 0; i < len(commonPrefix); i++ {
			if i >= len(line) || line[i] != commonPrefix[i] {
				commonPrefix = commonPrefix[:i]
				break
			}
		}

		if commonPrefix == "" {
			break
		}
	}

	// If no common prefix found, return as-is
	if commonPrefix == "" {
		return lines
	}

	// Remove common prefix from all lines
	result := make([]string, len(lines))
	prefixLen := len(commonPrefix)
	for i, line := range lines {
		if strings.TrimSpace(line) == "" {
			result[i] = ""
		} else if strings.HasPrefix(line, commonPrefix) {
			result[i] = line[prefixLen:]
		} else {
			result[i] = line
		}
	}

	return result
}

// hasAcceptableLineLength checks if all lines in the snippet are within maxLength
func hasAcceptableLineLength(snippet string, maxLength int) bool {
	lines := strings.Split(snippet, "\n")
	for _, line := range lines {
		if len(line) > maxLength {
			return false
		}
	}
	return true
}

// breakLongLines breaks lines that exceed maxLength at appropriate points
func breakLongLines(lines []string, maxLength int) []string {
	var result []string

	for _, line := range lines {
		if len(line) <= maxLength {
			result = append(result, line)
			continue
		}

		// Try to break the line intelligently
		broken := breakLine(line, maxLength)
		result = append(result, broken...)
	}

	return result
}

// breakLine breaks a single line at appropriate points
func breakLine(line string, maxLength int) []string {
	// If the line is short enough, return as-is
	if len(line) <= maxLength {
		return []string{line}
	}

	// Get the indentation of the original line
	indent := ""
	for _, ch := range line {
		if ch == ' ' || ch == '\t' {
			indent += string(ch)
		} else {
			break
		}
	}

	// Common break points in order of preference
	breakPoints := []string{
		", ",   // After comma
		" && ", // Before logical operators
		" || ",
		" + ", // Before arithmetic operators
		" - ",
		" * ",
		" / ",
		" = ", // Before assignment
		" := ",
		" == ", // Before comparison
		" != ",
		" < ",
		" > ",
		" <= ",
		" >= ",
		"(", // After opening parenthesis
		" ", // Any space
	}

	var result []string
	remaining := line
	isFirstLine := true

	for len(remaining) > maxLength {
		// Find the best break point
		bestBreak := -1

		for _, breakPoint := range breakPoints {
			// Look for break point before maxLength
			searchIn := remaining
			if len(searchIn) > maxLength {
				searchIn = remaining[:maxLength]
			}

			idx := strings.LastIndex(searchIn, breakPoint)
			if idx > 0 && idx < maxLength {
				// For some break points, we want to break after them
				if breakPoint == ", " || breakPoint == "(" {
					idx += len(breakPoint)
				}
				if idx > bestBreak {
					bestBreak = idx
				}
			}
		}

		// If no good break point found, break at maxLength
		if bestBreak == -1 {
			bestBreak = maxLength
		}

		// Add the line
		lineToAdd := remaining[:bestBreak]
		if !isFirstLine && !strings.HasPrefix(strings.TrimSpace(lineToAdd), "//") {
			// Add extra indentation for continuation
			lineToAdd = indent + "  " + strings.TrimLeft(lineToAdd, " \t")
		}
		result = append(result, strings.TrimRight(lineToAdd, " "))

		// Update remaining
		remaining = remaining[bestBreak:]
		if !isFirstLine && !strings.HasPrefix(strings.TrimSpace(remaining), "//") {
			remaining = strings.TrimLeft(remaining, " ")
		}
		isFirstLine = false
	}

	// Add the last part
	if len(remaining) > 0 {
		if !isFirstLine && !strings.HasPrefix(strings.TrimSpace(remaining), "//") {
			remaining = indent + "  " + strings.TrimLeft(remaining, " \t")
		}
		result = append(result, remaining)
	}

	return result
}