package views

import (
	"sync"

	"github.com/charmbracelet/glamour"
	"github.com/charmbracelet/glamour/styles"
	"github.com/muesli/termenv"
)

type mdCacheKey struct {
	width int
	src   string
}

var (
	mdMu       sync.Mutex
	mdRenderer *glamour.TermRenderer
	mdWidth    int
	mdCache    = map[mdCacheKey]string{}
)

// RenderMarkdown renders Markdown to ANSI using a cached glamour renderer.
//
// Important: we intentionally use a fixed dark style — NOT WithAutoStyle().
// AutoStyle calls termenv.HasDarkBackground(), which sends an OSC query to the
// terminal and waits up to ~5s for a reply. In Cursor/some PTYs that reply
// never arrives, so the TUI appears to hang on startup (first selected ticket
// with a description triggers the renderer in ensureVisible/View).
func RenderMarkdown(src string, width int) string {
	if src == "" {
		return ""
	}
	if width < 20 {
		width = 20
	}

	key := mdCacheKey{width: width, src: src}
	mdMu.Lock()
	defer mdMu.Unlock()

	if out, ok := mdCache[key]; ok {
		return out
	}

	r, err := getRenderer(width)
	if err != nil {
		return src
	}
	out, err := r.Render(src)
	if err != nil {
		return src
	}
	for len(out) > 0 && (out[len(out)-1] == '\n' || out[len(out)-1] == ' ') {
		out = out[:len(out)-1]
	}
	if len(mdCache) > 128 {
		mdCache = map[mdCacheKey]string{}
	}
	mdCache[key] = out
	return out
}

func getRenderer(width int) (*glamour.TermRenderer, error) {
	if mdRenderer != nil && mdWidth == width {
		return mdRenderer, nil
	}
	r, err := glamour.NewTermRenderer(
		glamour.WithStyles(styles.DarkStyleConfig),
		glamour.WithWordWrap(width),
		glamour.WithColorProfile(termenv.ANSI256),
		glamour.WithEmoji(),
	)
	if err != nil {
		return nil, err
	}
	mdRenderer = r
	mdWidth = width
	return r, nil
}

// ClearMarkdownCache drops cached renders (e.g. after theme change).
func ClearMarkdownCache() {
	mdMu.Lock()
	defer mdMu.Unlock()
	mdCache = map[mdCacheKey]string{}
	mdRenderer = nil
	mdWidth = 0
}