package markdown

import (
	"bytes"
	"fmt"
	"strings"

	"gopkg.in/yaml.v3"
)

// ParsedContent represents a markdown file with frontmatter
type ParsedContent struct {
	Frontmatter map[string]interface{}
	Content     string
}

// Parse extracts YAML frontmatter and markdown content from a file
func Parse(input string) (*ParsedContent, error) {
	// Check if the file starts with frontmatter delimiter
	if !strings.HasPrefix(input, "---\n") && !strings.HasPrefix(input, "---\r\n") {
		// No frontmatter, return entire content as markdown
		return &ParsedContent{
			Frontmatter: make(map[string]interface{}),
			Content:     input,
		}, nil
	}

	// Find the end of frontmatter
	lines := strings.Split(input, "\n")
	endIdx := -1

	for i := 1; i < len(lines); i++ {
		trimmed := strings.TrimSpace(lines[i])
		if trimmed == "---" {
			endIdx = i
			break
		}
	}

	// If we didn't find the closing delimiter, treat as no frontmatter
	if endIdx == -1 {
		return &ParsedContent{
			Frontmatter: make(map[string]interface{}),
			Content:     input,
		}, nil
	}

	// Extract frontmatter YAML (between the delimiters)
	frontmatterLines := lines[1:endIdx]
	frontmatterYAML := strings.Join(frontmatterLines, "\n")

	// Parse YAML
	var frontmatter map[string]interface{}
	if err := yaml.Unmarshal([]byte(frontmatterYAML), &frontmatter); err != nil {
		return nil, fmt.Errorf("failed to parse frontmatter YAML: %w", err)
	}

	// Extract content (everything after the closing delimiter)
	contentLines := lines[endIdx+1:]
	content := strings.Join(contentLines, "\n")
	// Trim leading newline if present
	content = strings.TrimPrefix(content, "\n")

	return &ParsedContent{
		Frontmatter: frontmatter,
		Content:     content,
	}, nil
}

// Serialize combines frontmatter and content back into a single string
func Serialize(frontmatter map[string]interface{}, content string) (string, error) {
	// If no frontmatter, return just the content
	if len(frontmatter) == 0 {
		return content, nil
	}

	// Marshal frontmatter to YAML
	var buf bytes.Buffer
	encoder := yaml.NewEncoder(&buf)
	encoder.SetIndent(2)

	if err := encoder.Encode(frontmatter); err != nil {
		return "", fmt.Errorf("failed to marshal frontmatter: %w", err)
	}

	if err := encoder.Close(); err != nil {
		return "", fmt.Errorf("failed to close encoder: %w", err)
	}

	// Combine with delimiters
	yamlStr := buf.String()
	// Remove trailing newline from YAML output
	yamlStr = strings.TrimSuffix(yamlStr, "\n")

	result := fmt.Sprintf("---\n%s\n---\n%s", yamlStr, content)
	return result, nil
}