"""
Professional Social Post Rendering Engine

Generates Instagram/LinkedIn/TikTok-optimized posts using design system principles.
Features multiple layouts, auto-scaling typography, and mobile-first design.
"""

import io
import os
import re
import math
import random
import httpx
from typing import Tuple, Optional, List
from loguru import logger
from PIL import Image, ImageDraw, ImageFont, ImageFilter
from src.utils.design_system import (
    TYPOGRAPHY, SPACING, LINE_HEIGHT, PALETTES, LAYOUT_TEMPLATES,
    LayoutType, AspectRatio, LayoutTemplate, ColorPalette,
    detect_content_type, ensure_readable, get_contrast_ratio,
)


# ─────────────────────────────────────────────────────────────────────────────
# FONT LOADING & CACHING
# ─────────────────────────────────────────────────────────────────────────────

_FONT_CACHE: dict = {}


def _ensure_fonts():
    """Download professional fonts for social posts."""
    import urllib.request
    
    font_dir = "/tmp/orbis_fonts"
    os.makedirs(font_dir, exist_ok=True)
    
    fonts = {
        "inter_bold": (
            f"{font_dir}/Inter-Bold.ttf",
            "https://github.com/rsms/inter/raw/master/docs/font-files/Inter-Bold.otf"
        ),
        "inter_regular": (
            f"{font_dir}/Inter-Regular.ttf",
            "https://github.com/rsms/inter/raw/master/docs/font-files/Inter-Regular.otf"
        ),
        "inter_semibold": (
            f"{font_dir}/Inter-SemiBold.ttf",
            "https://github.com/rsms/inter/raw/master/docs/font-files/Inter-SemiBold.otf"
        ),
    }
    
    for key, (path, url) in fonts.items():
        if not os.path.exists(path):
            try:
                urllib.request.urlretrieve(url, path)
                logger.info(f"[Render] Downloaded font: {path}")
            except Exception as e:
                logger.warning(f"[Render] Font download failed ({key}): {e}")


def _load_font(size: int, weight: str = "regular") -> ImageFont.FreeTypeFont:
    """Load font with caching. Weights: regular, bold, semibold."""
    cache_key = (size, weight)
    if cache_key in _FONT_CACHE:
        return _FONT_CACHE[cache_key]
    
    # Attempt downloads
    _ensure_fonts()
    
    # Try loading from cache directory
    font_dir = "/tmp/orbis_fonts"
    weight_map = {
        "regular": "Inter-Regular.ttf",
        "semibold": "Inter-SemiBold.ttf",
        "bold": "Inter-Bold.ttf",
    }
    
    font_name = weight_map.get(weight, "Inter-Regular.ttf")
    font_path = os.path.join(font_dir, font_name)
    
    if os.path.exists(font_path):
        try:
            font = ImageFont.truetype(font_path, size)
            _FONT_CACHE[cache_key] = font
            return font
        except Exception as e:
            logger.warning(f"[Render] Could not load {font_path}: {e}")
    
    # Fallback to system fonts
    system_paths = {
        "bold": [
            "C:/Windows/Fonts/arialbd.ttf",
            "C:/Windows/Fonts/calibrib.ttf",
            "/usr/share/fonts/truetype/dejavu/DejaVuSans-Bold.ttf",
        ],
        "regular": [
            "C:/Windows/Fonts/arial.ttf",
            "C:/Windows/Fonts/calibri.ttf",
            "/usr/share/fonts/truetype/dejavu/DejaVuSans.ttf",
        ],
    }
    
    paths = system_paths.get(weight, system_paths["regular"])
    for path in paths:
        if os.path.exists(path):
            try:
                font = ImageFont.truetype(path, size)
                _FONT_CACHE[cache_key] = font
                return font
            except Exception:
                continue
    
    # Last resort
    return ImageFont.load_default()


# ─────────────────────────────────────────────────────────────────────────────
# TEXT UTILITIES
# ─────────────────────────────────────────────────────────────────────────────

def _wrap_text(text: str, font: ImageFont.FreeTypeFont, max_width: int, 
               draw: ImageDraw.ImageDraw) -> List[str]:
    """
    Wrap text intelligently for readability.
    
    Breaks on words, respects max_width, and returns list of lines.
    """
    words = text.split()
    if not words:
        return []
    
    lines = []
    current_line = ""
    
    for word in words:
        test_line = (current_line + " " + word).strip()
        bbox = draw.textbbox((0, 0), test_line, font=font)
        line_width = bbox[2] - bbox[0]
        
        if line_width <= max_width:
            current_line = test_line
        else:
            if current_line:
                lines.append(current_line)
            current_line = word
    
    if current_line:
        lines.append(current_line)
    
    return lines


def _get_text_height(text: str, font: ImageFont.FreeTypeFont, 
                     draw: ImageDraw.ImageDraw) -> int:
    """Get height of rendered text."""
    bbox = draw.textbbox((0, 0), text, font=font)
    return bbox[3] - bbox[1]


def _parse_caption(caption: str) -> Tuple[str, List[str], str]:
    """Parse LLM caption into hook, body lines, and hashtags."""
    # Remove structural markers
    clean = re.sub(
        r"(?im)^(HOOK|SLIDE\s*\d+[:\.\-]?[^|\n]*\|?|CAPTION|IMAGE_PROMPT)[:\s]*",
        "", caption
    )
    clean = re.sub(r"\n{3,}", "\n\n", clean).strip()
    
    lines = [l.strip() for l in clean.splitlines() if l.strip()]
    
    # Find hashtags (last line usually)
    tag_line = ""
    if lines:
        last_line = lines[-1]
        if all(w.startswith("#") for w in last_line.split() if w):
            tag_line = last_line
            lines = lines[:-1]
    
    # Split into hook and body
    hook = lines[0] if lines else "Untitled"
    body = lines[1:] if len(lines) > 1 else []
    
    return hook, body, tag_line


# ─────────────────────────────────────────────────────────────────────────────
# GRADIENT & BACKGROUND UTILITIES
# ─────────────────────────────────────────────────────────────────────────────

def _create_gradient_background(width: int, height: int, 
                               top_rgb: Tuple[int, int, int],
                               bot_rgb: Tuple[int, int, int],
                               angle: float = 90.0) -> Image.Image:
    """Create smooth vertical gradient background."""
    canvas = Image.new("RGB", (width, height))
    draw = ImageDraw.Draw(canvas)
    
    for y in range(height):
        # Linear interpolation
        t = y / height
        r = int(top_rgb[0] + (bot_rgb[0] - top_rgb[0]) * t)
        g = int(top_rgb[1] + (bot_rgb[1] - top_rgb[1]) * t)
        b = int(top_rgb[2] + (bot_rgb[2] - top_rgb[2]) * t)
        draw.line([(0, y), (width, y)], fill=(r, g, b))
    
    return canvas


def _add_scrim(image: Image.Image, top_opacity: int = 0, 
               bottom_opacity: int = 180, bottom_start: float = 0.4) -> Image.Image:
    """Add dark scrim overlay for text readability over images."""
    width, height = image.size
    
    if image.mode != "RGBA":
        image = image.convert("RGBA")
    
    scrim = Image.new("RGBA", (width, height), (0, 0, 0, 0))
    draw = ImageDraw.Draw(scrim)
    
    # Top scrim (subtle)
    if top_opacity > 0:
        top_h = int(height * 0.15)
        for i in range(top_h):
            alpha = int(top_opacity * (i / top_h))
            draw.line([(0, i), (width, i)], fill=(0, 0, 0, alpha))
    
    # Bottom scrim (strong)
    if bottom_opacity > 0:
        bot_start = int(height * bottom_start)
        bot_h = height - bot_start
        for i in range(bot_h):
            alpha = int(bottom_opacity * (i / bot_h) ** 0.7)
            draw.line([(0, bot_start + i), (width, bot_start + i)], 
                     fill=(0, 0, 0, alpha))
    
    return Image.alpha_composite(image, scrim)


# ─────────────────────────────────────────────────────────────────────────────
# LAYOUT IMPLEMENTATIONS
# ─────────────────────────────────────────────────────────────────────────────

class PostRenderer:
    """Main rendering engine for social posts."""
    
    def __init__(self, template: LayoutTemplate, palette: ColorPalette):
        self.template = template
        self.palette = palette
        self.width = template.aspect_ratio.width
        self.height = template.aspect_ratio.height
        self.margin = template.margin
    
    def render_typography_bold(self, hook: str, body: List[str], 
                              tags: str) -> Image.Image:
        """
        Typography-Bold Layout:
        - Large, readable headline
        - Subtle body text
        - High contrast gradient
        """
        canvas = _create_gradient_background(
            self.width, self.height,
            self.palette.bg_top, self.palette.bg_bottom
        )
        draw = ImageDraw.Draw(canvas)
        
        # Text color with contrast
        text_color = ensure_readable(
            self.palette.text_primary, self.palette.bg_top
        )
        
        # 1. Render headline with auto-scaling
        headline_size = self.template.headline_size
        headline_font = _load_font(headline_size, weight="bold")
        
        # Wrap headline
        wrapped_headline = _wrap_text(
            hook, headline_font, self.template.inner_width, draw
        )
        
        # If too many lines, reduce size
        while len(wrapped_headline) > 5 and headline_size > 48:
            headline_size -= 8
            headline_font = _load_font(headline_size, weight="bold")
            wrapped_headline = _wrap_text(
                hook, headline_font, self.template.inner_width, draw
            )
        
        # Calculate vertical centering
        line_height = int(headline_size * LINE_HEIGHT["tight"])
        total_headline_height = len(wrapped_headline) * line_height
        
        body_size = int(self.template.body_size * 0.8)
        body_font = _load_font(body_size, weight="regular")
        
        # Body text wrapping
        wrapped_body = []
        for line in body[:2]:  # Max 2 body lines
            wrapped_body.extend(
                _wrap_text(line, body_font, self.template.inner_width, draw)[:2]
            )
        
        body_line_height = int(body_size * LINE_HEIGHT["normal"])
        total_body_height = len(wrapped_body) * body_line_height
        
        gap = SPACING.lg
        total_height = total_headline_height + (gap + total_body_height if wrapped_body else 0)
        y = (self.height - total_height) // 2
        
        # 2. Draw accent bar
        bar_height = 6
        bar_width = min(
            self.template.inner_width,
            max(SPACING.lg, int(headline_size * 0.4))
        )
        draw.rectangle(
            [(self.margin, y - 24), (self.margin + bar_width, y - 18)],
            fill=self.palette.accent_primary
        )
        
        # 3. Draw headline
        for line in wrapped_headline:
            draw.text(
                (self.margin, y), line,
                font=headline_font,
                fill=text_color
            )
            y += line_height
        
        # 4. Draw body
        if wrapped_body:
            y += gap
            for line in wrapped_body:
                draw.text(
                    (self.margin, y), line,
                    font=body_font,
                    fill=(*text_color[:3], 220)
                )
                y += body_line_height
        
        # 5. Draw hashtags (bottom)
        if tags:
            tag_font = _load_font(TYPOGRAPHY.caption, weight="regular")
            draw.text(
                (self.margin, self.height - SPACING.lg - 10),
                tags[:100],
                font=tag_font,
                fill=(*self.palette.accent_primary, 180)
            )
        
        # 6. Draw brand watermark
        brand_font = _load_font(TYPOGRAPHY.tiny, weight="regular")
        brand_text = "@dailywireup"
        brand_bbox = draw.textbbox((0, 0), brand_text, font=brand_font)
        brand_width = brand_bbox[2] - brand_bbox[0]
        draw.text(
            (self.width - self.margin - brand_width - 8, self.height - SPACING.lg - 10),
            brand_text,
            font=brand_font,
            fill=(*text_color[:3], 100)
        )
        
        return canvas
    
    def render_editorial_photo(self, hook: str, body: List[str], 
                              tags: str, image_url: str) -> Image.Image:
        """
        Editorial-Photo Layout:
        - Full-bleed image with smart cropping
        - Dark scrim for text readability
        - Large headline positioned strategically
        """
        # Download and process image
        image = self._fetch_and_crop_image(image_url)
        if image is None:
            # Fallback to text-only
            return self.render_typography_bold(hook, body, tags)
        
        # Add dark scrim for text readability
        canvas = self._add_scrim(image, top_opacity=80, bottom_opacity=220)
        draw = ImageDraw.Draw(canvas)
        
        # Text color is always white for editorials
        text_color = (255, 255, 255)
        
        # 1. Top bar with branding
        brand_font = _load_font(28, weight="semibold")
        draw.text(
            (self.margin, SPACING.lg),
            "@dailywireup",
            font=brand_font,
            fill=(*self.palette.accent_primary, 240)
        )
        draw.rectangle(
            [(self.margin, SPACING.xl), (self.width - self.margin, SPACING.xl + 4)],
            fill=(*self.palette.accent_primary, 180)
        )
        
        # 2. Calculate headline positioning
        HEADLINE_START = int(self.height * 0.55)
        PADDING_BOTTOM = SPACING.xl
        
        headline_size = self.template.headline_size
        headline_font = _load_font(headline_size, weight="bold")
        
        wrapped_headline = _wrap_text(
            hook.upper(), headline_font, self.template.inner_width, draw
        )
        
        # Auto-scale if needed
        while len(wrapped_headline) > 4 and headline_size > 56:
            headline_size -= 8
            headline_font = _load_font(headline_size, weight="bold")
            wrapped_headline = _wrap_text(
                hook.upper(), headline_font, self.template.inner_width, draw
            )
        
        # 3. Draw headline with drop shadow
        line_height = int(headline_size * LINE_HEIGHT["tight"])
        y = HEADLINE_START
        
        for line in wrapped_headline:
            # Drop shadow
            draw.text(
                (self.margin + 3, y + 3), line,
                font=headline_font,
                fill=(0, 0, 0, 120)
            )
            # Main text
            draw.text(
                (self.margin, y), line,
                font=headline_font,
                fill=text_color
            )
            y += line_height
        
        # 4. Draw left accent bar
        bar_x = self.margin - 16
        draw.rectangle(
            [(bar_x, HEADLINE_START),
             (bar_x + 8, HEADLINE_START + len(wrapped_headline) * line_height)],
            fill=(*self.palette.accent_primary, 240)
        )
        
        # 5. Draw body text (sub-headline)
        body_size = int(self.template.body_size * 0.9)
        body_font = _load_font(body_size, weight="regular")
        y += SPACING.md
        
        for body_line in body[:2]:
            wrapped = _wrap_text(
                body_line, body_font, self.template.inner_width, draw
            )[:1]
            for line in wrapped:
                draw.text(
                    (self.margin, y), line,
                    font=body_font,
                    fill=(210, 210, 210, 210)
                )
                y += int(body_size * LINE_HEIGHT["normal"])
        
        # 6. Hashtags (bottom left)
        if tags:
            tag_font = _load_font(TYPOGRAPHY.caption, weight="regular")
            draw.text(
                (self.margin, self.height - SPACING.lg - 10),
                tags[:80],
                font=tag_font,
                fill=(*self.palette.accent_primary, 200)
            )
        
        return canvas.convert("RGB")
    
    def render_split_half(self, hook: str, body: List[str], 
                         tags: str, image_url: str) -> Image.Image:
        """
        Split-Half Layout:
        - Left: image
        - Right: text content
        """
        # Download and process image
        image = self._fetch_and_crop_image(image_url, crop_to_half=True)
        if image is None:
            return self.render_typography_bold(hook, body, tags)
        
        # Resize image to fit left half
        half_width = self.width // 2
        image = image.resize((half_width, self.height), Image.LANCZOS)
        
        # Create right half background
        right_bg = _create_gradient_background(
            half_width, self.height,
            self.palette.bg_top, self.palette.bg_bottom
        )
        
        # Composite
        canvas = Image.new("RGB", (self.width, self.height))
        canvas.paste(image, (0, 0))
        canvas.paste(right_bg, (half_width, 0))
        draw = ImageDraw.Draw(canvas)
        
        # Text on right side
        text_margin = SPACING.md
        text_width = half_width - (2 * text_margin)
        text_color = ensure_readable(
            self.palette.text_primary, self.palette.bg_top
        )
        
        # Headline
        headline_font = _load_font(self.template.headline_size - 20, weight="bold")
        wrapped_headline = _wrap_text(
            hook, headline_font, text_width, draw
        )
        
        y = SPACING.xl
        line_height = int(headline_font.size * LINE_HEIGHT["tight"])
        
        for line in wrapped_headline:
            draw.text(
                (half_width + text_margin, y), line,
                font=headline_font,
                fill=text_color
            )
            y += line_height
        
        # Body
        y += SPACING.md
        body_font = _load_font(self.template.body_size - 4, weight="regular")
        
        for body_line in body[:2]:
            wrapped = _wrap_text(
                body_line, body_font, text_width, draw
            )[:2]
            for line in wrapped:
                draw.text(
                    (half_width + text_margin, y), line,
                    font=body_font,
                    fill=text_color
                )
                y += int(body_font.size * LINE_HEIGHT["normal"])
            y += SPACING.md
        
        return canvas
    
    def _fetch_and_crop_image(self, image_url: str, crop_to_half: bool = False) -> Optional[Image.Image]:
        """Download and intelligently crop image to aspect ratio."""
        try:
            async_client = httpx.Client()
            resp = async_client.get(image_url, timeout=30, follow_redirects=True)
            resp.raise_for_status()
            image = Image.open(io.BytesIO(resp.content)).convert("RGB")
        except Exception as e:
            logger.error(f"[Render] Image fetch failed: {e}")
            return None
        
        # Determine target dimensions
        target_w = self.width if not crop_to_half else self.width // 2
        target_h = self.height
        target_ratio = target_w / target_h
        
        # Crop to aspect ratio
        img_w, img_h = image.size
        img_ratio = img_w / img_h
        
        if img_ratio > target_ratio:
            # Image too wide
            new_w = int(img_h * target_ratio)
            left = (img_w - new_w) // 2
            image = image.crop((left, 0, left + new_w, img_h))
        else:
            # Image too tall
            new_h = int(img_w / target_ratio)
            top = (img_h - new_h) // 2
            image = image.crop((0, top, img_w, top + new_h))
        
        # Resize to target
        image = image.resize((target_w, target_h), Image.LANCZOS)
        return image


# ─────────────────────────────────────────────────────────────────────────────
# PUBLIC API
# ─────────────────────────────────────────────────────────────────────────────

async def create_social_post(
    caption: str,
    image_url: Optional[str] = None,
    cloudinary_config: dict = None,
    layout_type: Optional[LayoutType] = None,
    palette_name: Optional[str] = None,
) -> str:
    """
    Generate a professional social media post.
    
    Args:
        caption: Post text (with optional hook, body, hashtags)
        image_url: Optional image URL for image-based layouts
        cloudinary_config: Config for uploading to Cloudinary
        layout_type: Specific layout to use (auto-selected if None)
        palette_name: Specific color palette (random if None)
    
    Returns:
        URL of generated post image
    """
    try:
        # Parse caption
        hook, body, tags = _parse_caption(caption)
        
        # Select palette
        if palette_name and palette_name in PALETTES:
            palette = PALETTES[palette_name]
        else:
            palette = random.choice(list(PALETTES.values()))
        
        # Select layout (smart selection)
        if layout_type is None:
            content_type = detect_content_type(hook, has_image=image_url is not None)
            word_count = len(hook.split())
            
            if word_count <= 10 and not image_url:
                layout_type = LayoutType.TYPOGRAPHY_BOLD
            elif image_url and word_count > 15:
                layout_type = LayoutType.EDITORIAL_PHOTO
            elif image_url and word_count <= 15:
                layout_type = LayoutType.SPLIT_HALF
            else:
                layout_type = LayoutType.TYPOGRAPHY_BOLD
        
        template = LAYOUT_TEMPLATES[layout_type]
        renderer = PostRenderer(template, palette)
        
        # Render based on layout
        logger.info(f"[Render] {layout_type.value} layout | {palette.name} palette")
        
        if layout_type == LayoutType.TYPOGRAPHY_BOLD:
            canvas = renderer.render_typography_bold(hook, body, tags)
        elif layout_type == LayoutType.EDITORIAL_PHOTO and image_url:
            canvas = renderer.render_editorial_photo(hook, body, tags, image_url)
        elif layout_type == LayoutType.SPLIT_HALF and image_url:
            canvas = renderer.render_split_half(hook, body, tags, image_url)
        else:
            canvas = renderer.render_typography_bold(hook, body, tags)
        
        # Upload to Cloudinary
        if cloudinary_config:
            buf = io.BytesIO()
            canvas.save(buf, format="JPEG", quality=95)
            buf.seek(0)
            
            import cloudinary
            import cloudinary.uploader
            cloudinary.config(**cloudinary_config)
            result = cloudinary.uploader.upload(
                buf, folder="ai_media_os/posts", resource_type="image"
            )
            url = result.get("secure_url", "")
            logger.info(f"[Render] Post uploaded: {url}")
            return url
        else:
            # Save locally for testing
            canvas.save("/tmp/post.jpg", quality=95)
            return "/tmp/post.jpg"
    
    except Exception as e:
        logger.error(f"[Render] Post generation failed: {e}")
        return image_url or ""