import subprocess
import shutil

from pathlib import Path
from jinja2 import Environment, FileSystemLoader
from config import Config


CONFIG = Config.from_yaml("config.yaml")

env = Environment(loader=FileSystemLoader("."))
template = env.get_template("template.html")


def convert_pdf_to_png(pdf_path: Path):
    png_path = pdf_path.with_suffix(".png")

    # Check if PNG exists and is newer than PDF (with 30 second buffer)
    if png_path.exists():
        pdf_mtime = pdf_path.stat().st_mtime
        png_mtime = png_path.stat().st_mtime
        if png_mtime >= (pdf_mtime + 30):  # 30 second buffer
            # PNG is up to date, no need to convert
            return
        else:
            print(f"PDF {pdf_path.name} is newer than PNG, reconverting...")

    print(f"Converting {pdf_path} → {png_path}")
    subprocess.run([
        "convert",
        "-density", str(CONFIG.png_dpi),
        str(pdf_path),
        "-quality", "95",
        str(png_path)
    ], check=True)


def needs_update(source_file: Path, target_file: Path) -> bool:
    """Check if target file needs to be updated based on source file modification time"""
    if not target_file.exists():
        return True

    source_mtime = source_file.stat().st_mtime
    target_mtime = target_file.stat().st_mtime

    # Return True if source is newer than target (with 30 second buffer)
    return source_mtime > (target_mtime + 30)


def build_gallery(source_dir: Path, web_dir: Path, relative_path: Path = None):
    """
    Build gallery for a directory, copying files to web directory and generating index.html

    Args:
        source_dir: Source directory containing PDFs
        web_dir: Target web directory
        relative_path: Relative path for navigation (None for root)
    """
    if relative_path is None:
        relative_path = Path(".")

    # Ensure web directory exists
    target_dir = web_dir / relative_path
    target_dir.mkdir(parents=True, exist_ok=True)

    # Find all PDFs in source directory
    pdfs = sorted(source_dir.glob("*.pdf"))
    items = []

    for pdf in pdfs:
        # Convert PDF to PNG in source directory
        convert_pdf_to_png(pdf)
        png_path = pdf.with_suffix(".png")

        # Copy both PDF and PNG to target directory only if needed
        target_pdf = target_dir / pdf.name
        target_png = target_dir / png_path.name

        if needs_update(pdf, target_pdf):
            print(f"Copying {pdf.name} to {target_pdf}")
            shutil.copy2(pdf, target_pdf)
        else:
            print(f"Skipping {pdf.name} (up to date)")

        if png_path.exists() and needs_update(png_path, target_png):
            print(f"Copying {png_path.name} to {target_png}")
            shutil.copy2(png_path, target_png)
        elif png_path.exists():
            print(f"Skipping {png_path.name} (up to date)")

        items.append({
            "name": pdf.name,
            "pdf_href": pdf.name,
            "png_href": png_path.name
        })

    # Find subdirectories in source
    subdirs = sorted([d.name for d in source_dir.iterdir() if d.is_dir()])

    # Generate index.html in target directory
    output_html = target_dir / "index.html"

    # Create a meaningful title
    if str(relative_path) == ".":
        title = "Gallery"
    else:
        title = f"Gallery: {relative_path}"

    with output_html.open("w") as f:
        f.write(template.render(
            title=title,
            items=items,
            subdirs=subdirs,
            relpath=str(relative_path)
        ))

    print(f"Generated {output_html}")

    # Recursively process subdirectories
    for subdir in subdirs:
        source_subdir = source_dir / subdir
        new_relative_path = relative_path / subdir
        build_gallery(source_subdir, web_dir, new_relative_path)


def loop_over_sources():
    web_root = Path(CONFIG.web_folder)

    for source in CONFIG.sources:
        print(f"Processing {source.name}: {source.path}")
        if source.path.is_dir():
            # Create a subdirectory based on plot_root and source name
            source_web_dir = web_root / CONFIG.plot_root / source.name
            build_gallery(source.path, source_web_dir)
            print(f"Processed {source.name}: {source.path}")
        elif source.path.suffix == ".pdf":
            # For single PDF files, copy to web root with plot_root and source name as directory
            source_web_dir = web_root / CONFIG.plot_root / source.name
            convert_pdf_to_png(source.path)
            png_path = source.path.with_suffix(".png")

            # Ensure web directory exists
            source_web_dir.mkdir(parents=True, exist_ok=True)

            # Copy PDF and PNG to web directory only if needed
            target_pdf = source_web_dir / source.path.name
            target_png = source_web_dir / png_path.name

            if needs_update(source.path, target_pdf):
                print(f"Copying {source.path.name} to {target_pdf}")
                shutil.copy2(source.path, target_pdf)
            else:
                print(f"Skipping {source.path.name} (up to date)")

            if png_path.exists() and needs_update(png_path, target_png):
                print(f"Copying {png_path.name} to {target_png}")
                shutil.copy2(png_path, target_png)
            elif png_path.exists():
                print(f"Skipping {png_path.name} (up to date)")

            # Create items list for template
            items = [{
                "name": source.path.name,
                "pdf_href": source.path.name,
                "png_href": png_path.name
            }]

            # Generate index.html for single PDF
            output_html = source_web_dir / "index.html"
            with output_html.open("w") as f:
                f.write(template.render(
                    title=source.name,
                    items=items,
                    subdirs=[],
                    relpath=source.name
                ))

            print(f"Generated {output_html}")
            print(f"Processed {source.name}: {source.path}")


if __name__ == "__main__":
    loop_over_sources()
    print("Done")