reader/viewer/model.go

package viewer

import (
	"fmt"
	"os"
	"path/filepath"
	"strings"

	"github.com/alecthomas/chroma/v2"
	"github.com/alecthomas/chroma/v2/formatters"
	"github.com/alecthomas/chroma/v2/lexers"
	"github.com/alecthomas/chroma/v2/styles"
	"github.com/charmbracelet/bubbles/viewport"
	"github.com/charmbracelet/glamour"
	"github.com/charmbracelet/lipgloss"
)

// ThemeConfig holds theme settings for rendering
type ThemeConfig struct {
	ChromaStyle   string
	GlamourStyle  string
	LineNumColor  string
	TextColor     string
}

// Model represents the content viewer
type Model struct {
	viewport    viewport.Model
	FilePath    string
	FileName    string
	content     string
	contentType string
	ready       bool
	width       int
	height      int
	theme       ThemeConfig
}

// New creates a new viewer model
func New() Model {
	return Model{
		theme: ThemeConfig{
			ChromaStyle:  "github",
			GlamourStyle: "light",
			LineNumColor: "#888888",
			TextColor:    "#1a1a1a",
		},
	}
}

// SetTheme updates the viewer's theme settings
func (m *Model) SetTheme(config ThemeConfig) {
	m.theme = config
	// Re-render if we have content
	if m.FilePath != "" {
		m.renderContent()
	}
}

// SetSize sets the viewer dimensions
func (m *Model) SetSize(width, height int) {
	m.width = width
	m.height = height

	if !m.ready {
		m.viewport = viewport.New(width, height)
		m.ready = true
	} else {
		m.viewport.Width = width
		m.viewport.Height = height
	}

	// Re-render content if we have a file
	if m.FilePath != "" {
		m.renderContent()
	}
}

// LoadFile loads and renders a file
func (m *Model) LoadFile(path string) error {
	content, err := os.ReadFile(path)
	if err != nil {
		return err
	}

	m.FilePath = path
	m.FileName = filepath.Base(path)
	m.content = string(content)
	m.contentType = detectContentType(path)
	m.renderContent()
	m.viewport.GotoTop()

	return nil
}

// renderContent renders the content based on file type
func (m *Model) renderContent() {
	if m.width <= 0 || m.height <= 0 {
		return
	}

	var rendered string

	switch m.contentType {
	case "markdown":
		rendered = m.renderMarkdown()
	case "code":
		rendered = m.renderCode()
	default:
		rendered = m.renderPlainText()
	}

	m.viewport.SetContent(rendered)
}

func (m *Model) renderMarkdown() string {
	r, err := glamour.NewTermRenderer(
		glamour.WithStylePath(m.theme.GlamourStyle),
		glamour.WithWordWrap(m.width-4),
	)
	if err != nil {
		return m.content
	}

	out, err := r.Render(m.content)
	if err != nil {
		return m.content
	}

	return out
}

func (m *Model) renderCode() string {
	lexer := lexers.Match(m.FilePath)
	if lexer == nil {
		lexer = lexers.Fallback
	}
	lexer = chroma.Coalesce(lexer)

	style := styles.Get(m.theme.ChromaStyle)
	if style == nil {
		style = styles.Fallback
	}

	formatter := formatters.Get("terminal256")
	if formatter == nil {
		formatter = formatters.Fallback
	}

	iterator, err := lexer.Tokenise(nil, m.content)
	if err != nil {
		return m.renderPlainText()
	}

	var buf strings.Builder
	err = formatter.Format(&buf, style, iterator)
	if err != nil {
		return m.renderPlainText()
	}

	// Add line numbers
	lines := strings.Split(buf.String(), "\n")
	lineNumStyle := lipgloss.NewStyle().Foreground(lipgloss.Color(m.theme.LineNumColor))

	var result strings.Builder
	for i, line := range lines {
		lineNum := fmt.Sprintf("%4d │ ", i+1)
		result.WriteString(lineNumStyle.Render(lineNum))
		result.WriteString(line)
		if i < len(lines)-1 {
			result.WriteString("\n")
		}
	}

	return result.String()
}

func (m *Model) renderPlainText() string {
	lineNumStyle := lipgloss.NewStyle().Foreground(lipgloss.Color(m.theme.LineNumColor))
	textStyle := lipgloss.NewStyle().Foreground(lipgloss.Color(m.theme.TextColor))

	lines := strings.Split(m.content, "\n")
	var result strings.Builder

	for i, line := range lines {
		lineNum := fmt.Sprintf("%4d │ ", i+1)
		result.WriteString(lineNumStyle.Render(lineNum))
		result.WriteString(textStyle.Render(line))
		if i < len(lines)-1 {
			result.WriteString("\n")
		}
	}

	return result.String()
}

func detectContentType(path string) string {
	ext := strings.ToLower(filepath.Ext(path))

	markdownExts := map[string]bool{
		".md":       true,
		".markdown": true,
		".mdown":    true,
		".mkd":      true,
	}

	codeExts := map[string]bool{
		".go": true, ".py": true, ".js": true, ".ts": true,
		".jsx": true, ".tsx": true, ".rs": true, ".c": true,
		".cpp": true, ".h": true, ".hpp": true, ".java": true,
		".rb": true, ".php": true, ".sh": true, ".bash": true,
		".zsh": true, ".json": true, ".yaml": true, ".yml": true,
		".toml": true, ".xml": true, ".html": true, ".css": true,
		".scss": true, ".sass": true, ".sql": true, ".lua": true,
		".vim": true, ".swift": true, ".kt": true, ".kts": true,
		".zig": true, ".nim": true, ".ex": true, ".exs": true,
		".erl": true, ".hrl": true, ".clj": true, ".scala": true,
	}

	if markdownExts[ext] {
		return "markdown"
	}
	if codeExts[ext] {
		return "code"
	}
	return "text"
}

// View renders the viewer
func (m Model) View() string {
	if !m.ready {
		return ""
	}
	return m.viewport.View()
}

// Viewport returns the viewport for external control
func (m *Model) Viewport() *viewport.Model {
	return &m.viewport
}

// ScrollPercent returns the current scroll percentage
func (m Model) ScrollPercent() float64 {
	return m.viewport.ScrollPercent()
}

// LineDown scrolls down one line
func (m *Model) LineDown() {
	m.viewport.LineDown(1)
}

// LineUp scrolls up one line
func (m *Model) LineUp() {
	m.viewport.LineUp(1)
}

// PageDown scrolls a full page down
func (m *Model) PageDown() {
	m.viewport.ViewDown()
}

// PageUp scrolls a full page up
func (m *Model) PageUp() {
	m.viewport.ViewUp()
}

// GotoTop scrolls to the top
func (m *Model) GotoTop() {
	m.viewport.GotoTop()
}

// GotoBottom scrolls to the bottom
func (m *Model) GotoBottom() {
	m.viewport.GotoBottom()
}

// Empty returns true if no file is loaded
func (m Model) Empty() bool {
	return m.FilePath == ""
}