import base64
import io
import json
import os
from typing import Dict, List, Tuple, Any, Optional
import time
import requests
from PIL import Image
import gradio as gr
import re


# =========================
# Config
# =========================
DEFAULT_API_URL = os.environ.get("API_URL")
TOKEN = os.environ.get("TOKEN")
LOGO_IMAGE_PATH = './assets/logo.jpg'
GOOGLE_FONTS_URL = "<link href='https://fonts.googleapis.com/css2?family=Noto+Sans+SC:wght@400;700&display=swap' rel='stylesheet'>"
LATEX_DELIMS = [
    {"left": "$$", "right": "$$", "display": True},
    {"left": "$",  "right": "$",  "display": False},
    {"left": "\\(", "right": "\\)", "display": False},
    {"left": "\\[", "right": "\\]", "display": True},
]
AUTH_HEADER = {"Authorization": f"bearer {TOKEN}"}
JSON_HEADERS = {**AUTH_HEADER, "Content-Type": "application/json"}


# =========================
# Base64 and Example Loading Logic
# =========================
def image_to_base64_data_url(filepath: str) -> str:
    """Reads a local image file and encodes it into a Base64 Data URL."""
    try:
        ext = os.path.splitext(filepath)[1].lower()
        mime_types = {'.jpg': 'image/jpeg', '.jpeg': 'image/jpeg', '.png': 'image/png', '.gif': 'image/gif'}
        mime_type = mime_types.get(ext, 'image/jpeg')
        with open(filepath, "rb") as image_file:
            encoded_string = base64.b64encode(image_file.read()).decode("utf-8")
        return f"data:{mime_type};base64,{encoded_string}"
    except Exception as e:
        print(f"Error encoding image to Base64: {e}")
        return ""

def _escape_inequalities_in_math(md: str) -> str:
    """
    Finds math blocks in a Markdown string and replaces < and > with
    their LaTeX equivalents, \lt and \gt, to prevent markdown parsing errors.
    """
    _MATH_PATTERNS = [
        re.compile(r"\$\$([\s\S]+?)\$\$"),
        re.compile(r"\$([^\$]+?)\$"),
        re.compile(r"\\\[([\s\S]+?)\\\]"),
        re.compile(r"\\\(([\s\S]+?)\\\)"),
    ]
    def fix(s: str) -> str:
        s = s.replace("<=", r" \le ").replace(">=", r" \ge ")
        s = s.replace("≤", r" \le ").replace("≥", r" \ge ")
        s = s.replace("<",  r" \lt ").replace(">",  r" \gt ")
        return s
    for pat in _MATH_PATTERNS:
        md = pat.sub(lambda m: m.group(0).replace(m.group(1), fix(m.group(1))), md)
    return md

def _get_examples_from_dir(dir_path: str) -> List[List[str]]:
    supported_exts = {".png", ".jpg", ".jpeg", ".bmp", ".webp"}
    examples = []
    if not os.path.exists(dir_path): return []
    for filename in sorted(os.listdir(dir_path)):
        if os.path.splitext(filename)[1].lower() in supported_exts:
            examples.append([os.path.join(dir_path, filename)])
    return examples

TARGETED_EXAMPLES_DIR = "examples/targeted"
COMPLEX_EXAMPLES_DIR = "examples/complex"
targeted_recognition_examples = _get_examples_from_dir(TARGETED_EXAMPLES_DIR)
complex_document_examples = _get_examples_from_dir(COMPLEX_EXAMPLES_DIR)

# =========================
# UI Helpers
# =========================
def render_uploaded_image_div(file_path: str) -> str:
    data_url = image_to_base64_data_url(file_path)
    return f"""
    <div class="uploaded-image">
        <img src="{data_url}" alt="Uploaded image" style="width:100%;height:100%;object-fit:contain;"/>
    </div>
    """

def update_preview_visibility(file_path: Optional[str]) -> Dict:
    if file_path:
        html_content = render_uploaded_image_div(file_path)
        return gr.update(value=html_content, visible=True)
    else:
        return gr.update(value="", visible=False)

def _on_gallery_select(example_paths: List[str], evt: gr.SelectData):
    try:
        idx = evt.index
        return example_paths[idx]
    except Exception:
        return None

# =========================
# API Call Logic
# =========================
def _file_to_b64_image_only(file_path: str) -> Tuple[str, int]:
    if not file_path: raise ValueError("Please upload an image first.")
    ext = os.path.splitext(file_path)[1].lower()
    if ext not in {".png", ".jpg", ".jpeg", ".bmp", ".webp"}: raise ValueError("Only image files are supported.")
    with open(file_path, "rb") as f:
        return base64.b64encode(f.read()).decode("utf-8"), 1

def _call_api(api_url: str, file_path: str, use_layout_detection: bool,
              prompt_label: Optional[str], use_chart_recognition: bool = False) -> Dict[str, Any]:
    b64, file_type = _file_to_b64_image_only(file_path)
    payload = {
        "file": b64,
        "useLayoutDetection": bool(use_layout_detection),
        "fileType": file_type,
        "layoutMergeBboxesMode": "union",
    }
    if not use_layout_detection:
        if not prompt_label:
            raise ValueError("Please select a recognition type.")
        payload["promptLabel"] = prompt_label.strip().lower()
    if use_layout_detection and use_chart_recognition:
        payload["useChartRecognition"] = True

    try:
        print(f"Sending API request to {api_url}...")
        start_time = time.time()
        resp = requests.post(api_url, json=payload, headers=JSON_HEADERS, timeout=600)
        end_time = time.time()
        duration = end_time - start_time
        print(f"Received API response in {duration:.2f} seconds.")
        
        resp.raise_for_status()
        data = resp.json()
    except requests.exceptions.RequestException as e:
        raise gr.Error(f"API request failed:{e}")
    except json.JSONDecodeError:
        raise gr.Error(f"Invalid JSON response from server:\n{getattr(resp, 'text', '')}")

    if data.get("errorCode", -1) != 0:
        raise gr.Error("API returned an error:")
    return data


# =========================
# API Response Processing
# =========================

# 【改动点】: 这个函数现在不再需要，因为我们不再将URL下载为PIL Image对象。
# def url_to_pil_image(url: str) -> Optional[Image.Image]:
#     """Downloads an image from a URL and returns it as a PIL Image object for the Gradio Image component."""
#     if not url or not url.startswith(('http://', 'https://')):
#         print(f"Warning: Invalid URL provided for visualization image: {url}")
#         return None
#     try:
#         start_time = time.time()
#         response = requests.get(url, timeout=600)
#         end_time = time.time()
#         print(f"Fetched visualization image from {url} in {end_time - start_time:.2f} seconds.")
#
#         response.raise_for_status()
#         image_bytes = response.content
#         pil_image = Image.open(io.BytesIO(image_bytes)).convert("RGB")
#         return pil_image
#     except requests.exceptions.RequestException as e:
#         print(f"Error fetching visualization image from URL {url}: {e}")
#         return None
#     except Exception as e:
#         print(f"Error processing visualization image from URL {url}: {e}")
#         return None

def _process_api_response_page(result: Dict[str, Any]) -> Tuple[str, str, str]:
    """
    Processes the API response.
    1. Replaces markdown image placeholders with their direct URLs.
    2. Constructs an HTML <img> tag string for the visualization image URL.
    """
    layout_results = (result or {}).get("layoutParsingResults", [])
    if not layout_results:
        return "No content was recognized.", "<p>No visualization available.</p>", ""

    page0 = layout_results[0] or {}

    # Step 1: Process Markdown content (unchanged from previous optimization)
    md_data = page0.get("markdown") or {}
    md_text = md_data.get("text", "") or ""
    md_images_map = md_data.get("images", {})
    if md_images_map:
        for placeholder_path, image_url in md_images_map.items():
            md_text = md_text.replace(f'src="{placeholder_path}"', f'src="{image_url}"') \
                             .replace(f']({placeholder_path})', f']({image_url})')

    # 【核心改动点】 Step 2: Process Visualization images by creating an HTML string
    output_html = "<p style='text-align:center; color:#888;'>No visualization image available.</p>"
    out_imgs = page0.get("outputImages") or {}
    
    # Get all image URLs and sort them
    sorted_urls = [img_url for _, img_url in sorted(out_imgs.items()) if img_url]

    # Logic to select the final visualization image URL
    output_image_url: Optional[str] = None
    if len(sorted_urls) >= 2:
        output_image_url = sorted_urls[1]
    elif sorted_urls:
        output_image_url = sorted_urls[0]

    # If a URL was found, create the <img> tag
    if output_image_url:
        print(f"Found visualization image URL: {output_image_url}")
        # The CSS will style this `img` tag because of the `#vis_image_doc img` selector
        output_html = f'<img src="{output_image_url}" alt="Detection Visualization">'
    else:
        print("Warning: No visualization image URL found in the API response.")

    md_text = _escape_inequalities_in_math(md_text)
    return md_text or "(Empty result)", output_html, md_text

# =========================
# Handlers
# =========================
def handle_complex_doc(file_path: str, use_chart_recognition: bool) -> Tuple[str, str, str]:
    if not file_path: raise gr.Error("Please upload an image first.")
    data = _call_api(DEFAULT_API_URL, file_path, use_layout_detection=True, prompt_label=None, use_chart_recognition=use_chart_recognition)
    result = data.get("result", {})
    # Note the return types now align with the new function signature
    return _process_api_response_page(result)

def handle_targeted_recognition(file_path: str, prompt_choice: str) -> Tuple[str, str]:
    if not file_path: raise gr.Error("Please upload an image first.")
    mapping = {"Text Recognition": "ocr", "Formula Recognition": "formula", "Table Recognition": "table", "Chart Recognition": "chart"}
    label = mapping.get(prompt_choice, "ocr")
    data = _call_api(DEFAULT_API_URL, file_path, use_layout_detection=False, prompt_label=label)
    result = data.get("result", {})
    md_preview, _, md_raw = _process_api_response_page(result)
    return md_preview, md_raw

# =========================
# CSS & UI
# =========================
custom_css = """
/* 全局字体 */
body, .gradio-container {
  font-family: "Noto Sans SC", "Microsoft YaHei", "PingFang SC", sans-serif;
}
/* ... (rest of the CSS is unchanged) ... */
.app-header { text-align: center; max-width: 900px; margin: 0 auto 8px !important; }
.gradio-container { padding: 4px 0 !important; }
.gradio-container [data-testid="tabs"], .gradio-container .tabs { margin-top: 0 !important; }
.gradio-container [data-testid="tabitem"], .gradio-container .tabitem { padding-top: 4px !important; }
.quick-links { text-align: center; padding: 8px 0; border: 1px solid #e5e7eb; border-radius: 8px; margin: 8px auto; max-width: 900px; }
.quick-links a { margin: 0 12px; font-size: 14px; font-weight: 600; color: #3b82f6; text-decoration: none; }
.quick-links a:hover { text-decoration: underline; }
.prompt-grid { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 6px; }
.prompt-grid button { height: 40px !important; padding: 0 12px !important; border-radius: 8px !important; font-weight: 600 !important; font-size: 13px !important; letter-spacing: 0.2px; }
#image_preview_vl, #image_preview_doc { height: 400px !important; overflow: auto; }
#image_preview_vl img, #image_preview_doc img, #vis_image_doc img { width: 100% !important; height: auto !important; object-fit: contain !important; display: block; }
#md_preview_vl, #md_preview_doc { max-height: 540px; min-height: 180px; overflow: auto; scrollbar-gutter: stable both-edges; }
#md_preview_vl .prose, #md_preview_doc .prose { line-height: 1.7 !important; }
#md_preview_vl .prose img, #md_preview_doc .prose img { display: block; margin: 0 auto; max-width: 100%; height: auto; }
.notice { margin: 8px auto 0; max-width: 900px; padding: 10px 12px; border: 1px solid #e5e7eb; border-radius: 8px; background: #f8fafc; font-size: 14px; line-height: 1.6; }
.notice strong { font-weight: 700; }
.notice a { color: #3b82f6; text-decoration: none; }
.notice a:hover { text-decoration: underline; }
"""

with gr.Blocks(head=GOOGLE_FONTS_URL, css=custom_css, theme=gr.themes.Soft()) as demo:
    logo_data_url = image_to_base64_data_url(LOGO_IMAGE_PATH) if os.path.exists(LOGO_IMAGE_PATH) else ""
    gr.HTML(f"""<div class="app-header"><img src="{logo_data_url}" alt="App Logo" style="max-height:10%; width: auto; margin: 10px auto; display: block;"></div>""")
    gr.HTML("""<div class="notice"><strong>Heads up:</strong> The Hugging Face demo can be slow at times. For a faster experience, please try <a href="https://aistudio.baidu.com/application/detail/98365" target="_blank" rel="noopener noreferrer">Baidu AI Studio</a> or <a href="https://modelscope.cn/studios/PaddlePaddle/PaddleOCR-VL_Online_Demo/summary" target="_blank" rel="noopener noreferrer">ModelScope</a>.</div>""")
    gr.HTML("""<div class="quick-links"><a href="https://github.com/PaddlePaddle/PaddleOCR" target="_blank">GitHub</a> | <a href="https://ernie.baidu.com/blog/publication/PaddleOCR-VL_Technical_Report.pdf" target="_blank">Technical Report</a> | <a href="https://huggingface.co/PaddlePaddle/PaddleOCR-VL" target="_blank">Model</a></div>""")
    
    with gr.Tabs():
        with gr.Tab("Document Parsing"):
            with gr.Row():
                with gr.Column(scale=5):
                    file_doc = gr.File(label="Upload Image", file_count="single", type="filepath", file_types=["image"])
                    preview_doc_html = gr.HTML(value="", elem_id="image_preview_doc", visible=False)
                    gr.Markdown("_( Use this mode for recognizing full-page documents with structured layouts, such as reports, papers, or magazines.)_")
                    gr.Markdown("💡 *To recognize a single, pre-cropped element (e.g., a table or formula), switch to the 'Element-level Recognition' tab for better results.*")
                    with gr.Row(variant="panel"):
                        chart_parsing_switch = gr.Checkbox(label="Enable chart parsing", value=False, scale=1)
                        btn_parse = gr.Button("Parse Document", variant="primary", scale=2)
                    if complex_document_examples:
                        complex_paths = [e[0] for e in complex_document_examples]
                        complex_state = gr.State(complex_paths)
                        gr.Markdown("**Document Examples (Click an image to load)**")
                        gallery_complex = gr.Gallery(value=complex_paths, columns=4, height=400, preview=False, label=None, allow_preview=False)
                        gallery_complex.select(fn=_on_gallery_select, inputs=[complex_state], outputs=[file_doc])

                with gr.Column(scale=7):
                    with gr.Tabs():
                        with gr.Tab("Markdown Preview"):
                            md_preview_doc = gr.Markdown("Please upload an image and click 'Parse Document'.", latex_delimiters=LATEX_DELIMS, elem_id="md_preview_doc")
                        with gr.Tab("Visualization"):
                            # 【核心改动点】: 将 gr.Image 替换为 gr.HTML
                            vis_image_doc = gr.HTML(label="Detection Visualization", elem_id="vis_image_doc")
                        with gr.Tab("Markdown Source"):
                            md_raw_doc = gr.Code(label="Markdown Source Code", language="markdown")

            file_doc.change(fn=update_preview_visibility, inputs=[file_doc], outputs=[preview_doc_html])
            btn_parse.click(fn=handle_complex_doc, inputs=[file_doc, chart_parsing_switch], outputs=[md_preview_doc, vis_image_doc, md_raw_doc])

        with gr.Tab("Element-level Recognition"):
            with gr.Row():
                with gr.Column(scale=5):
                    file_vl = gr.File(label="Upload Image", file_count="single", type="filepath", file_types=["image"])
                    preview_vl_html = gr.HTML(value="", elem_id="image_preview_vl", visible=False)
                    gr.Markdown("_(Best for images with a **simple, single-column layout** (e.g., pure text), or for a **pre-cropped single element** like a table, formula, or chart.)_")
                    gr.Markdown("Choose a recognition type:")
                    with gr.Row(elem_classes=["prompt-grid"]):
                        btn_ocr = gr.Button("Text Recognition", variant="secondary")
                        btn_formula = gr.Button("Formula Recognition", "secondary")
                    with gr.Row(elem_classes=["prompt-grid"]):
                        btn_table = gr.Button("Table Recognition", variant="secondary")
                        btn_chart = gr.Button("Chart Recognition", variant="secondary")
                    if targeted_recognition_examples:
                        targeted_paths = [e[0] for e in targeted_recognition_examples]
                        targeted_state = gr.State(targeted_paths)
                        gr.Markdown("**Element-level Recognition Examples (Click an image to load)**")
                        gallery_targeted = gr.Gallery(value=targeted_paths, columns=4, height=400, preview=False, label=None, allow_preview=False)
                        gallery_targeted.select(fn=_on_gallery_select, inputs=[targeted_state], outputs=[file_vl])

                with gr.Column(scale=7):
                    with gr.Tabs():
                        with gr.Tab("Recognition Result"):
                            md_preview_vl = gr.Markdown("Please upload an image and click a recognition type.", latex_delimiters=LATEX_DELIMS, elem_id="md_preview_vl")
                        with gr.Tab("Raw Output"):
                            md_raw_vl = gr.Code(label="Raw Output", language="markdown")

            file_vl.change(fn=update_preview_visibility, inputs=[file_vl], outputs=[preview_vl_html])
            btn_ocr.click(fn=handle_targeted_recognition, inputs=[file_vl, gr.State("Text Recognition")], outputs=[md_preview_vl, md_raw_vl])
            btn_formula.click(fn=handle_targeted_recognition, inputs=[file_vl, gr.State("Formula Recognition")], outputs=[md_preview_vl, md_raw_vl])
            btn_table.click(fn=handle_targeted_recognition, inputs=[file_vl, gr.State("Table Recognition")], outputs=[md_preview_vl, md_raw_vl])
            btn_chart.click(fn=handle_targeted_recognition, inputs=[file_vl, gr.State("Chart Recognition")], outputs=[md_preview_vl, md_raw_vl])

if __name__ == "__main__":
    port = int(os.getenv("PORT", "7860"))
    demo.queue(max_size=6).launch(server_name="0.0.0.0", server_port=port,share=False)