package channelbridge

import (
	"math/rand"
	"regexp"
	"strings"
	"time"
)

// This file holds the chat-reply sanitizer used before a reply is delivered to an
// IM channel adapter (design/17 §2 + the role-play convention: the Web client
// renders <action>/<narration> as muted italic; IM channels must receive plain chat
// text only, with the action/monologue markup removed).

var (
	// pairedRoleplayRe matches a complete <action>...</action> / <narration>...</narration>
	// block including its inner text, so an action/monologue is dropped wholesale before
	// IM delivery. Non-greedy and case-insensitive to tolerate a model that emits <Action>.
	pairedRoleplayRe = regexp.MustCompile(`(?is)<(action|narration)\b[^>]*?>.*?</(action|narration)\s*>`)
	// strayRoleplayRe matches any remaining single opening/closing role-play tag (for a
	// malformed or unpaired emission).
	strayRoleplayRe = regexp.MustCompile(`(?is)</?(action|narration)\b[^>]*?>`)
	// paragraphRe matches <p>...</p> / <p/> paragraph markers, keeping the inner text.
	paragraphRe = regexp.MustCompile(`(?is)</?p\b[^>]*?>`)
	// blankLinesRe collapses runs of blank lines left behind after stripping.
	blankLinesRe = regexp.MustCompile(`\n\s*\n+`)
)

// stripNarration returns the plain chat text of a reply with role-play/action/
// narration markup removed, paragraph markers flattened and blank-line runs
// collapsed. It never raises or panics on malformed input; a reply that was only an
// action/monologue becomes an empty string (caller may then skip the send).
func stripNarration(text string) string {
	if strings.TrimSpace(text) == "" {
		return ""
	}
	s := pairedRoleplayRe.ReplaceAllString(text, "")
	s = strayRoleplayRe.ReplaceAllString(s, "")
	s = paragraphRe.ReplaceAllString(s, "")
	s = blankLinesRe.ReplaceAllString(s, "\n")
	return strings.TrimSpace(s)
}

// paragraphBlockRe matches an entire <p>...</p> block, capturing its inner text
// (design: each <p> is one chat bubble; the Web client renders each as its own
// bubble and the IM adapters deliver each as its own message).
var paragraphBlockRe = regexp.MustCompile(`(?is)<p\b[^>]*?>(.*?)</p\s*>`)

// splitBubbles turns a reply into the list of chat bubbles it carries, in order.
// Each <p>...</p> block is one bubble, with role-play/action/narration stripped from
// its text; empty bubbles are dropped. A reply with no <p> markers is treated as a
// single bubble (newlines preserved). A pure action/monologue yields an empty slice.
func splitBubbles(text string) []string {
	if !strings.Contains(strings.ToLower(text), "<p") {
		if c := stripNarration(text); c != "" {
			return []string{c}
		}
		return nil
	}
	out := make([]string, 0)
	for _, m := range paragraphBlockRe.FindAllStringSubmatch(text, -1) {
		if c := stripNarration(m[1]); c != "" {
			out = append(out, c)
		}
	}
	if len(out) == 0 {
		// <p> markers present but no well-formed block — fall back to whole text.
		if c := stripNarration(text); c != "" {
			out = append(out, c)
		}
	}
	return out
}

// bubbleGap returns a randomized 0.5s..2s delay used between IM outbound bubbles so a
// burst of paragraphs doesn't flood the channel (design/17 §2). The Web frontend is
// not affected — it renders all bubbles from the persisted stream without any delay.
// It is only consulted when a reply carries more than one bubble.
func bubbleGap() time.Duration {
	return 500*time.Millisecond + time.Duration(rand.Float64()*1500)*time.Millisecond
}