jiang13-bbs/backend/markdown/legacy_rewrite.go

package markdown

import (
	"strconv"
	"strings"
)

// RewriteLegacyDirectives 将旧式 :::hide / :::timeline / 裸 ::: 改写为行级 BBCode。
// 幂等：已是 BBCode 的内容原样返回（若无旧标记）。代码围栏内不改写。
func RewriteLegacyDirectives(content string) string {
	if content == "" {
		return content
	}
	if !strings.Contains(content, ":::") {
		return content
	}
	lines := splitLines(content)
	var out []string
	inCode := false
	i := 0
	for i < len(lines) {
		trimmed := strings.TrimSpace(lines[i])
		if strings.HasPrefix(trimmed, "```") {
			inCode = !inCode
			out = append(out, lines[i])
			i++
			continue
		}
		if inCode {
			out = append(out, lines[i])
			i++
			continue
		}

		if kind, pts, pwd, locked, ok := parseLegacyHideOpen(trimmed); ok {
			bodyLines := make([]string, 0)
			j := i + 1
			innerCode := false
			found := false
			for j < len(lines) {
				inner := strings.TrimSpace(lines[j])
				if strings.HasPrefix(inner, "```") {
					innerCode = !innerCode
					bodyLines = append(bodyLines, lines[j])
					j++
					continue
				}
				if innerCode {
					bodyLines = append(bodyLines, lines[j])
					j++
					continue
				}
				if inner == ":::" {
					found = true
					break
				}
				bodyLines = append(bodyLines, lines[j])
				j++
			}
			out = append(out, openMarkerLine(kind, pts, pwd, locked))
			out = append(out, bodyLines...)
			if found {
				out = append(out, "[/hide]")
				i = j + 1
			} else {
				// 未闭合：仍写出已转换开标记与正文，避免丢内容
				i = j
			}
			continue
		}

		if trimmed == ":::timeline" || strings.HasPrefix(trimmed, ":::timeline ") {
			bodyLines := make([]string, 0)
			j := i + 1
			innerCode := false
			found := false
			for j < len(lines) {
				inner := strings.TrimSpace(lines[j])
				if strings.HasPrefix(inner, "```") {
					innerCode = !innerCode
					bodyLines = append(bodyLines, lines[j])
					j++
					continue
				}
				if innerCode {
					bodyLines = append(bodyLines, lines[j])
					j++
					continue
				}
				if inner == ":::" {
					found = true
					break
				}
				bodyLines = append(bodyLines, lines[j])
				j++
			}
			out = append(out, "[timeline]")
			out = append(out, bodyLines...)
			if found {
				out = append(out, "[/timeline]")
				i = j + 1
			} else {
				i = j
			}
			continue
		}

		out = append(out, lines[i])
		i++
	}
	return strings.Join(out, "\n")
}

// parseLegacyHideOpen 解析旧式 :::hide <kind> [arg] [locked]
func parseLegacyHideOpen(trimmed string) (kind string, points int, password string, locked bool, ok bool) {
	if !strings.HasPrefix(trimmed, ":::hide") {
		return "", 0, "", false, false
	}
	rest := strings.TrimSpace(trimmed[len(":::hide"):])
	if rest == "" {
		return "", 0, "", false, false
	}
	parts := strings.Fields(rest)
	if len(parts) == 0 {
		return "", 0, "", false, false
	}
	kind = parts[0]
	switch kind {
	case HideKindLogin, HideKindReply, HideKindPoints, HideKindPassword:
	default:
		return "", 0, "", false, false
	}
	idx := 1
	if kind == HideKindPoints {
		if idx >= len(parts) {
			return "", 0, "", false, false
		}
		n, err := strconv.Atoi(parts[idx])
		if err != nil {
			return "", 0, "", false, false
		}
		points = n
		idx++
	} else if kind == HideKindPassword {
		if idx < len(parts) && parts[idx] != "locked" {
			password = parts[idx]
			idx++
		}
	}
	for ; idx < len(parts); idx++ {
		if parts[idx] == "locked" {
			locked = true
		} else {
			return "", 0, "", false, false
		}
	}
	return kind, points, password, locked, true
}