package channelbridge

import (
	"math/rand"
	"regexp"
	"strings"
	"time"
	"unicode/utf8"
)

// 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+`)
	// starRoleplayRe matches a full-width star-wrapped block ＊...＊ — the drift
	// form when the model forgets the <action>/<narration> XML tags. The body is
	// captured so a non-role-play full-width emphasis can be left alone.
	starRoleplayRe = regexp.MustCompile(`(?s)＊([\s\S]*?)＊`)
	// halfStarRoleplayRe matches a half-width star block that clearly carries a
	// role-play keyword (动作/旁白/内心/神态/轻声), so *动作：弯起眼睛* is stripped
	// while plain markdown *emphasis* is left untouched.
	halfStarRoleplayRe = regexp.MustCompile(`(?s)\*((?:动作|旁白|内心|神态|轻声)\s*[:：]?[\s\S]*?)\*`)
)

// shortRoleplayRunes caps how long a keyword-less full-width star block may be
// and still be treated as a role-play remark (design §9.5: conservative — a long
// keyword-less ＊...＊ paragraph is left as text rather than dropped wholesale).
const shortRoleplayRunes = 40

// 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 = starRoleplayRe.ReplaceAllStringFunc(s, func(m string) string {
		if isStarRoleplay(strings.TrimSpace(strings.TrimSuffix(strings.TrimPrefix(m, "＊"), "＊"))) {
			return ""
		}
		return m
	})
	s = halfStarRoleplayRe.ReplaceAllString(s, "")
	s = paragraphRe.ReplaceAllString(s, "")
	s = blankLinesRe.ReplaceAllString(s, "\n")
	return strings.TrimSpace(s)
}

// isStarRoleplay reports whether a full-width star block ＊...＊ holds a role-play
// remark: it carries a role-play keyword, or it is a short stand-alone fragment
// (no newline, no long body) — the drift shape ＊弯起眼睛＊. A long keyword-less
// paragraph wrapped in stars is kept so a real message is not dropped.
func isStarRoleplay(inner string) bool {
	t := strings.TrimSpace(inner)
	if t == "" {
		return false
	}
	if hasRoleplayPrefix(t) {
		return true
	}
	return !strings.Contains(t, "\n") && utf8.RuneCountInString(t) <= shortRoleplayRunes
}

// hasRoleplayPrefix reports whether the block starts with a role-play keyword.
func hasRoleplayPrefix(t string) bool {
	for _, p := range []string{"动作", "旁白", "内心", "神态", "轻声"} {
		if strings.HasPrefix(t, p) {
			return true
		}
	}
	return false
}

// 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
}