srt_utils.py

import re

def srt_time_to_seconds(timestamp):
    """Converts SRT timestamp (HH:MM:SS,mmm) to seconds"""
    try:
        time_part, ms_part = timestamp.split(",")
        h, m, s = map(int, time_part.split(":"))
        ms = int(ms_part)
        return h * 3600 + m * 60 + s + ms / 1000.0
    except:
        return 0.0

def seconds_to_srt_time(seconds):
    """Converts seconds to SRT timestamp (HH:MM:SS,mmm)"""
    hours = int(seconds // 3600)
    minutes = int((seconds % 3600) // 60)
    secs = int(seconds % 60)
    ms = int((seconds % 1) * 1000)
    return f"{hours:02d}:{minutes:02d}:{secs:02d},{ms:03d}"

def shift_srt_timestamps(srt_content, offset_seconds):
    """Shifts all timestamps in SRT content by offset_seconds"""
    subs = parse_srt(srt_content)
    if not subs:
        return srt_content
        
    shifted_srt = ""
    for i, sub in enumerate(subs, 1):
        start = sub['start'] + offset_seconds
        end = sub['end'] + offset_seconds
        
        # Ensure non-negative
        if start < 0: start = 0
        if end < 1e-3: end = 1e-3 # avoid 0 overlap logic issues if possible
        
        start_str = seconds_to_srt_time(start)
        end_str = seconds_to_srt_time(end)
        
        shifted_srt += f"{i}\n{start_str} --> {end_str}\n{sub['text']}\n\n"
        
    return shifted_srt.strip()

def parse_srt(srt_content):
    """Parses SRT content into a list of dictionaries. Returns VALIDATED list."""
    pattern = re.compile(r"(\d+)\s*\n([^-\n]+?) --> ([^-\n]+?)\s*\n((?:(?!\d+\s*\n\d{1,2}:\d{2}).+\n?)*)", re.MULTILINE)
    matches = pattern.findall(srt_content)
    
    subtitles = []
    for num, start, end, text in matches:
        subtitles.append({
            'start': srt_time_to_seconds(start.strip()),
            'end': srt_time_to_seconds(end.strip()),
            'text': text.strip()
        })
    return subtitles

def format_text_lines(text, max_chars=42):
    """Formats text into max 2 lines, balancing length or respecting max_chars"""
    words = text.split()
    if not words:
        return ""
    
    # If fits in one line, but we might WANT to split if it's long (> 30 chars) for better reading (pyramid shape)
    # The user complained about 42 chars being too long for one line.
    FORCE_SPLIT_THRESHOLD = 30
    
    if len(text) <= max_chars and len(text) <= FORCE_SPLIT_THRESHOLD:
        return text
    
    # Needs splitting (or we want to try splitting)
    # Simple split strategy: find middle space
    best_split_idx = -1
    best_balance = float('inf')
    
    # Try splitting at each word
    for i in range(1, len(words)):
        # Construct line 1 and line 2
        line1 = " ".join(words[:i])
        line2 = " ".join(words[i:])
        
        len1 = len(line1)
        len2 = len(line2)
        
        # Valid split? Only if both fit max_chars 
        if len1 <= max_chars and len2 <= max_chars:
            balance = abs(len2 - len1)
            # Bonus for bottom heavy (line2 >= line1) which looks better often (pyramid)
            if len2 >= len1:
                balance -= 5 
            
            if balance < best_balance:
                best_balance = balance
                best_split_idx = i
                
    # If we found a valid split
    if best_split_idx != -1:
        # If the original text fit in one line (< max_chars), only use the split if it's reasonably balanced.
        # If the split results in a tiny orphan like "I\nam going", stick to 1 line if possible.
        if len(text) <= max_chars:
             line1 = " ".join(words[:best_split_idx])
             line2 = " ".join(words[best_split_idx:])
             # If one line is very short relative to the other, maybe don't split?
             # But user wants "Netflix style", usually balanced.  
             pass 

        line1 = " ".join(words[:best_split_idx])
        line2 = " ".join(words[best_split_idx:])
        return f"{line1}\n{line2}"
    
    # Fallback: if no valid split found (e.g. words too long), but whole text fits in max_chars
    if len(text) <= max_chars:
        return text
        
    # Fallback 2: Really long text, just split in middle
    mid = len(words) // 2
    return " ".join(words[:mid]) + "\n" + " ".join(words[mid:])

def fix_word_timing(words):
    """
    Ensures words are sequential in time.
    Strategy:
    1. If overlaps, prefer trimming the END of the previous word to preserve the START of the current word.
    2. Only delay the current word if the previous word would become too short or inverted.
    3. Ensure minimum duration for all words.
    """
    if not words: return []
    
    # We edit in place / return modified list
    
    for i in range(1, len(words)):
        prev = words[i-1]
        curr = words[i]
        
        # Check for overlap
        if curr['start'] < prev['end']:
            # Overlap detected.
            # Try to trim prev['end'] to match curr['start']
            
            # Check if trimming leaves prev with enough time? (e.g. > 0s)
            # Actually, standard logic: just clamp prev end.
            new_prev_end = max(prev['start'], curr['start'])
            
            # If trimming makes it zero/negative (meaning curr starts BEFORE prev starts),
            # then we adhere to sequential text order implies we MUST delay curr.
            if new_prev_end <= prev['start'] + 0.01:
                # Impossible to trim prev enough. Push curr.
                curr['start'] = prev['end']
            else:
                # Trim prev
                prev['end'] = new_prev_end
        
        # Ensure curr has valid duration
        if curr['end'] <= curr['start']:
            curr['end'] = curr['start'] + 0.1 # Minimum duration 100ms
            
    return words

def apply_netflix_style_filter(srt_content):
    """
    Groups word-level subtitles into Netflix-style phrases.
    Rules:
    - Max 42 chars/line
    - Max 2 lines
    - Max duration 7s
    - Merge words
    """
    words = parse_srt(srt_content)
    if not words:
        return srt_content
        
    # FIX TIMING ISSUES FIRST
    words = fix_word_timing(words)

    grouped_events = []
    current_group = []
    
    MAX_CHARS_PER_LINE = 42
    MAX_LINES = 2
    MAX_TOTAL_CHARS = MAX_CHARS_PER_LINE * MAX_LINES
    MAX_DURATION = 7.0
    MIN_GAP_FOR_SPLIT = 0.5 # seconds
    
    def get_group_text(group):
        return " ".join(w['text'] for w in group)
    
    def get_group_duration(group):
         if not group: return 0
         return group[-1]['end'] - group[0]['start']

    for i, word in enumerate(words):
        if not current_group:
            current_group.append(word)
            continue
            
        last_word = current_group[-1]
        
        # 1. Check for Silence (Gap)
        gap = word['start'] - last_word['end']
        if gap > MIN_GAP_FOR_SPLIT:
            grouped_events.append(current_group)
            current_group = [word]
            continue
            
        # 2. Check Limits (Length & Duration)
        current_text = get_group_text(current_group)
        new_text_proj = current_text + " " + word['text']
        current_duration = last_word['end'] - current_group[0]['start']
        new_duration_proj = word['end'] - current_group[0]['start']
        
        # New Logic: Prefer single lines
        # If adding the word exceeds 42 chars (MAX_CHARS_PER_LINE)
        if len(new_text_proj) > MAX_CHARS_PER_LINE:
            # We are crossing the single line boundary.
            # Check if we SHOULD split now or allow 2 lines.
            
            # Reasons to split (make a new subtitle):
            # A. Current subtitle is already "long enough" in duration (> 1s)
            is_long_enough_dur = current_duration > 1.0 
            
            # B. Current subtitle is a complete sentence? 
            # (Handled by step 3, but this is size check)
            
            # C. The projected text is HUGE (e.g. > 70 chars). 
            # Netflix allows up to 84 (2 lines), but user wants "separation".
            # Let's cap at something smaller for 2 lines, e.g. 70.
            is_too_huge = len(new_text_proj) > 70
            
            # If it's long enough duration OR becoming huge -> BREAK
            if is_long_enough_dur or is_too_huge:
                grouped_events.append(current_group)
                current_group = [word]
                continue
            
            # Otherwise, allow merging into 2nd line (e.g. fast speech, short duration)
        
        # Check absolute absolute URL limit (MAX_TOTAL_CHARS) just in case
        if len(new_text_proj) > MAX_TOTAL_CHARS or new_duration_proj > MAX_DURATION:
            grouped_events.append(current_group)
            current_group = [word]
            continue
            
        # 3. Check Sentence Endings (CRITICAL)
        # If previous word was a sentence end, ALWAYS split, unless current group is tiny (<15 chars)
        if re.search(r'[.!?]$', last_word['text']):
             # Exception: "No." (Very short). "again." (6 chars) will break.
             if len(current_text) > 3: 
                 grouped_events.append(current_group)
                 current_group = [word]
                 continue
                 
        current_group.append(word)

    if current_group:
        grouped_events.append(current_group)
        
    # --- POST-PROCESSING: Merge Orphans ---
    # Attempt to merge single/short words into previous block if they are close
    
    merged_events = []
    if grouped_events:
        merged_events.append(grouped_events[0])
        
        for i in range(1, len(grouped_events)):
            prev_group = merged_events[-1]
            curr_group = grouped_events[i]
            
            # Check if current group is "orphan-candidate"
            # Criteria: 1 word OR very short text (< 10 chars)
            curr_text = get_group_text(curr_group)
            is_orphan = len(curr_group) == 1 or len(curr_text) < 10
            
            if is_orphan:
                # Check gap
                gap = curr_group[0]['start'] - prev_group[-1]['end']
                
                # If gap is small enough (user said "very close")
                # Let's say < 1.0s is reasonably close for a "continuation"
                if gap < 1.0: 
                    # Check if merging breaks limits
                    # We need to simulate the merge
                    combined_text = get_group_text(prev_group + curr_group)
                    formatted = format_text_lines(combined_text, MAX_CHARS_PER_LINE)
                    lines = formatted.split('\n')
                    
                    # Valid if max 2 lines and lines aren't too long (format_text_lines handles length balancing, 
                    # but we check if it forced 3 lines or something weird, though helper only does max 2 usually)
                    # format_text_lines guarantees max 2 lines usually, unless it fails fallback.
                    
                    # Check char limit on lines just to be safe
                    valid_merge = True
                    for line in lines:
                        if len(line) > MAX_CHARS_PER_LINE + 5: # Tolerance
                             valid_merge = False
                             break
                    
                    if valid_merge:
                         # MERGE!
                         prev_group.extend(curr_group)
                         continue

            # If not merged, append
            merged_events.append(curr_group)

    # Generate Output SRT
    output_srt = ""
    for i, group in enumerate(merged_events, 1):
        if not group: continue
        
        start_time = seconds_to_srt_time(group[0]['start'])
        end_time = seconds_to_srt_time(group[-1]['end'])
        
        text = get_group_text(group)
        formatted_text = format_text_lines(text, MAX_CHARS_PER_LINE)
        
        output_srt += f"{i}\n{start_time} --> {end_time}\n{formatted_text}\n\n"
        
    return output_srt.strip()

import subprocess
import shutil
import os

def process_audio_for_transcription(input_file: str, has_bg_music: bool = False, time_start: float = None, time_end: float = None) -> str:
    """
    Process audio to maximize speech clarity.
    
    Args:
        input_file: Path to input audio
        has_bg_music: If True, uses Demucs to remove background music (slow).
                      If False, skips Demucs but applies voice enhancement filters (fast).
    
    Returns path to processed .mp3 file (vocals)
    """
    
    # Output directory for processed files
    output_dir = os.path.join("static", "processed")
    os.makedirs(output_dir, exist_ok=True)
    
    input_filename = os.path.basename(input_file)
    input_stem = os.path.splitext(input_filename)[0]
    
    # Adicionar sufixo se houver corte, para evitar cache/conflito incorreto
    suffix = ""
    if time_start is not None: suffix += f"_s{int(time_start)}"
    if time_end is not None: suffix += f"_e{int(time_end)}"
    
    final_output = os.path.join(output_dir, f"{input_stem}{suffix}.processed.mp3")

    ffmpeg_cmd = shutil.which("ffmpeg")
    if not ffmpeg_cmd:
        print("⚠️ FFmpeg não encontrado!")
        return input_file

    vocals_path = input_file
    
    # 1. Background Music Removal (Demucs) - OPTIONAL
    if has_bg_music:
        print(f"🔊 [Demucs] Iniciando isolamento de voz via AI (has_bg_music=True)...")
        demucs_output_dir = os.path.join("static", "separated")
        os.makedirs(demucs_output_dir, exist_ok=True)
        
        # Check demucs availability
        demucs_cmd = shutil.which("demucs")
        if not demucs_cmd:
            demucs_cmd = "demucs" # Fallback to path alias

        try:
            model = "htdemucs"
            command = [
                demucs_cmd,
                "--two-stems=vocals",
                "-n", model,
                "-d", "cpu",
                "--mp3",
                "--mp3-bitrate", "128",
                input_file,
                "-o", demucs_output_dir
            ]
            
            print(f"🔊 Executando Demucs...")
            result = subprocess.run(command, check=False, stdout=subprocess.PIPE, stderr=subprocess.PIPE, text=True)
            
            if result.returncode == 0:
                # Demucs success
                # Path: output_dir / model_name / input_filename_no_ext / vocals.mp3
                demucs_vocals = os.path.join(demucs_output_dir, model, input_stem, "vocals.mp3")
                if os.path.exists(demucs_vocals):
                    print(f"✅ Demucs sucesso: {demucs_vocals}")
                    vocals_path = demucs_vocals
            else:
                print(f"⚠️ Erro no Demucs (Code {result.returncode}), continuando com audio original.")
                
        except Exception as e:
            print(f"⚠️ Falha no Demucs: {e}")
            
    else:
        print(f"⏩ [Demucs] Pulando remoção de música (has_bg_music=False).")

    # 2. Voice Enhancement (FFmpeg Filters) - ALWAYS RUN
    print(f"🔊 [FFmpeg] Aplicando filtros de melhoria de voz...")
    
    # Compress to mono mp3 16k with aggressive voice enhancement
    # Filters include highpass, noise reduction, compression, EQ, and normalization
    filter_chain = (
        "highpass=f=100,"
        "afftdn=nr=10:nf=-50:tn=1,"
        "compand=attacks=0:points=-80/-90|-45/-25|-27/-9|0/-7:gain=5,"
        "equalizer=f=3000:width_type=h:width=1000:g=5,"
        "loudnorm"
    )

    cmd_convert = [
        ffmpeg_cmd, "-y",
        "-i", vocals_path,
    ]
    
    # Apply cutting if requested (Output seeking for accuracy)
    if time_start is not None:
        cmd_convert.extend(["-ss", str(time_start)])
    if time_end is not None:
        cmd_convert.extend(["-to", str(time_end)])
        
    cmd_convert.extend([
        "-ac", "1", "-ar", "16000",
        "-af", filter_chain,
        "-c:a", "libmp3lame", "-q:a", "2",
        final_output
    ])
    
    try:
        subprocess.run(cmd_convert, check=True, stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
        
        # Cleanup demucs folder if it was used
        if has_bg_music and "separated" in vocals_path:
             try: 
                 # We need to find the parent folder of 'vocals.mp3' which is the song folder
                 song_folder = os.path.dirname(vocals_path)
                 shutil.rmtree(song_folder)
             except: pass
             
        return final_output
        
    except Exception as e:
        print(f"⚠️ Erro no FFmpeg: {e}")
        return vocals_path