# SPDX-License-Identifier: Apache-2.0
# adapted from vllm: https://github.com/vllm-project/vllm/blob/v0.7.3/docs/source/generate_examples.py

import itertools
import os
import re
from dataclasses import dataclass, field
from pathlib import Path

ROOT_DIR = Path(__file__).parent.parent.resolve()
ROOT_DIR_RELATIVE = '../..'
EXAMPLE_DIR = ROOT_DIR / "examples"
EXAMPLE_DOC_DIR = ROOT_DIR / "docs/getting_started/examples"
GITHUB_REPO = "hao-ai-lab/FastVideo"  # Update this to your repo
GENERATED_DOC_PREFIXES = (
    "examples/",
    "getting_started/examples/",
    "inference/examples/",
    "training/examples/",
    "distillation/examples/",
)


def fix_case(text: str) -> str:
    subs = {
        "api": "API",
        "cli": "CLI",
        "cpu": "CPU",
        "llm": "LLM",
        "tpu": "TPU",
        "aqlm": "AQLM",
        "gguf": "GGUF",
        "lora": "LoRA",
        "rlhf": "RLHF",
        "vllm": "vLLM",
        "openai": "OpenAI",
        "multilora": "MultiLoRA",
        "mlpspeculator": "MLPSpeculator",
        "finetune": "Finetune",
        "distillation": "Distillation",
        "wan": "Wan",
        "i2v": "I2V",
        "t2v": "T2V",
        "1.3b": "1.3B",
        "14b": "14B",
        "480p": "480P",
        "720p": "720P",
        r"fp\d+": lambda x: x.group(0).upper(),  # e.g. fp16, fp32
        r"int\d+": lambda x: x.group(0).upper(),  # e.g. int8, int16
    }
    for pattern, repl in subs.items():
        text = re.sub(rf'\b{pattern}\b', repl, text, flags=re.IGNORECASE)  # type: ignore[call-overload]
    return text


@dataclass
class Index:
    """
    Index class to generate a structured document index.

    Attributes:
        path (Path): The path save the index file to.
        title (str): The title of the index.
        description (str): A brief description of the index.
        caption (str): An optional caption for the table of contents.
        maxdepth (int): The maximum depth of the table of contents. Defaults to 1.
        documents (list[str]): A list of document paths to include in the index. Defaults to an empty list.

    Methods:
        generate() -> str:
            Generates the index content as a string in the specified format.
    """ # noqa: E501
    path: Path
    title: str
    description: str
    caption: str
    maxdepth: int = 1
    documents: list[str] = field(default_factory=list)

    def generate(self) -> str:
        content = f"# {self.title}\n\n{self.description}\n\n"
        if self.caption:
            content += f"## {self.caption}\n\n"
        # Generate a simple list of links for MkDocs
        for doc in self.documents:
            # Convert document path to proper link
            doc_link = doc.replace("\\", "/")
            # Get just the filename for the link text
            doc_title = fix_case(Path(doc).stem.replace("_", " ").title())
            content += f"- [{doc_title}]({doc_link}.md)\n"
        content += "\n"
        return content


@dataclass
class Example:
    """
    Example class for generating documentation content from a given path.

    Attributes:
        path (Path): The path to the main directory or file.
        category (str): The category of the document.
        main_file (Path): The main file in the directory.
        other_files (list[Path]): list of other files in the directory.
        title (str): The title of the document.

    Methods:
        __post_init__(): Initializes the main_file, other_files, and title attributes.
        determine_main_file() -> Path: Determines the main file in the given path.
        determine_other_files() -> list[Path]: Determines other files in the directory excluding the main file.
        determine_title() -> str: Determines the title of the document.
        generate() -> str: Generates the documentation content.
    """ # noqa: E501
    path: Path
    category: str | None = None
    main_file: Path = field(init=False)
    other_files: list[Path] = field(init=False)
    title: str = field(init=False)

    def __post_init__(self):
        self.main_file = self.determine_main_file()
        self.other_files = self.determine_other_files()
        self.title = self.determine_title()

    def determine_main_file(self) -> Path:
        """
        Determines the main file in the given path.
        If the path is a file, it returns the path itself. Otherwise, it searches
        for Markdown files (*.md) in the directory and returns the first one found.
        Returns:
            Path: The main file path, either the original path if it's a file or the first
            Markdown file found in the directory.
        Raises:
            IndexError: If no Markdown files are found in the directory.
        """ # noqa: E501
        if self.path.is_file():
            return self.path

        markdown_files = sorted(self.path.glob("*.md"))
        if not markdown_files:
            raise IndexError(f"No Markdown files found in {self.path}")

        readme_files = [f for f in markdown_files if f.name.lower() == "readme.md"]
        if readme_files:
            return readme_files[0]

        return markdown_files[0]

    def determine_other_files(self) -> list[Path]:
        """
        Determine other files in the directory excluding the main file.

        This method checks if the given path is a file. If it is, it returns an empty list.
        Otherwise, it recursively searches through the directory and returns a list of all
        files that are not the main file.

        Returns:
            list[Path]: A list of Path objects representing the other files in the directory.
        """ # noqa: E501
        if self.path.is_file():
            return []
        is_other_file = lambda file: file.is_file() and file != self.main_file
        return [file for file in self.path.rglob("*") if is_other_file(file)]  # type: ignore[no-untyped-call]

    def determine_title(self) -> str:
        return fix_case(self.path.stem.replace("_", " ").title())

    def generate(self) -> str:
        # Create GitHub link to source
        github_path = str(self.path.relative_to(ROOT_DIR)).replace("\\", "/")
        github_url = f"https://github.com/{GITHUB_REPO}/blob/main/{github_path}"
        content = f"**Source:** [{github_path}]({github_url})\n\n"

        # Add title for code files
        if self.main_file.suffix != ".md":
            content += f"# {self.title}\n\n"

        # Include main file content
        if self.main_file.suffix == ".md":
            # For markdown files, include the content directly
            with open(self.main_file, encoding='utf-8') as f:
                content += f.read() + "\n\n"
        else:
            # For code files, use code blocks
            language = self.main_file.suffix[1:] if self.main_file.suffix else ""
            with open(self.main_file, encoding='utf-8') as f:
                file_content = f.read()
            content += f"```{language}\n{file_content}\n```\n\n"

        if not self.other_files:
            return content

        content += "## Additional Files\n\n"
        # Define binary/non-text file extensions to skip
        binary_extensions = {
            '.mp4', '.avi', '.mov', '.mkv', '.gif', '.jpg', '.jpeg', '.png', '.webp', '.bmp', '.pdf', '.zip', '.tar',
            '.gz', '.mp3', '.wav'
        }

        for file in sorted(self.other_files):
            # Skip binary files
            if file.suffix.lower() in binary_extensions:
                continue

            file_rel_path = file.relative_to(self.path)
            # Use collapsible admonition syntax for MkDocs
            content += f"??? note \"{file_rel_path}\"\n\n"

            try:
                if file.suffix == ".md":
                    # Include markdown content with indentation
                    with open(file, encoding='utf-8') as f:
                        for line in f:
                            content += f"    {line}"
                else:
                    # Include code with proper formatting
                    language = file.suffix[1:] if file.suffix else ""
                    with open(file, encoding='utf-8') as f:
                        file_content = f.read()
                    # Indent the code block for the admonition
                    content += f"    ```{language}\n"
                    for line in file_content.split('\n'):
                        content += f"    {line}\n"
                    content += "    ```\n"
                content += "\n"
            except UnicodeDecodeError:
                # Skip files that can't be decoded as UTF-8
                continue

        return content


@dataclass
class NestedStructure:
    """Helper class to manage nested documentation structures for training/distillation."""
    category: str
    method: str
    model: str
    dataset: str
    example: Example

    @property
    def filename(self) -> str:
        return f"{self.model}_{self.dataset}"

    @property
    def title(self) -> str:
        return fix_case(self.dataset.replace('_', ' '))

    @property
    def description(self) -> str:
        category_name = self.category.title()
        return f"{category_name} example using the {self.dataset} dataset with the {self.model} model."


def create_category_indices() -> dict[str, Index]:
    """Create category indices with their respective configurations."""
    main_index_dir = ROOT_DIR / "docs/examples"
    if not main_index_dir.exists():
        main_index_dir.mkdir(parents=True)

    category_indices = {
        "inference":
        Index(
            path=ROOT_DIR / "docs/inference/examples/examples_inference_index.md",
            title="🚀 Examples",
            description=
            "Inference examples demonstrate how to use FastVideo inference. We recommend starting with [basic.md](basic.md).",
            caption="Examples",
            maxdepth=1,
        ),
        "training":
        Index(
            path=ROOT_DIR / "docs/training/examples/examples_training_index.md",
            title="🚀 Examples",
            description="Training examples demonstrate how to use FastVideo training.",
            caption="Examples",
            maxdepth=3,
        ),
        "distillation":
        Index(
            path=ROOT_DIR / "docs/distillation/examples/examples_distillation_index.md",
            title="🚀 Examples",
            description="Distillation examples demonstrate how to use FastVideo distillation.",
            caption="Examples",
            maxdepth=3,
        ),
    }

    # Ensure all category doc directories exist
    for index in category_indices.values():
        if not index.path.parent.exists():
            index.path.parent.mkdir(parents=True)

    return category_indices


def find_examples(category_indices: dict[str, Index], generate_main_index: bool) -> list[Example]:
    """Find all examples from the examples directory."""
    examples = []
    glob_patterns = ["*.py", "*.md", "*.sh"]

    # Map category names to actual directory names
    category_dir_mapping = {
        "distillation": "distill",  # examples/distill/ -> distillation category
    }

    # Find categorised examples
    for category in category_indices:
        # Use mapped directory name if available, otherwise use category name
        dir_name = category_dir_mapping.get(category, category)
        category_dir = EXAMPLE_DIR / dir_name

        # Skip if directory doesn't exist
        if not category_dir.exists():
            continue

        globs = [category_dir.glob(pattern) for pattern in glob_patterns]
        for path in itertools.chain(*globs):
            examples.append(Example(path, category))
        # Find examples in subdirectories (recursively)
        for path in category_dir.glob("**/*.md"):
            examples.append(Example(path.parent, category))

    # Find uncategorised examples only if we're generating a main index
    if generate_main_index:
        globs = [EXAMPLE_DIR.glob(pattern) for pattern in glob_patterns]
        for path in itertools.chain(*globs):
            examples.append(Example(path))
        # Find examples in subdirectories
        for path in EXAMPLE_DIR.glob("*/*.md"):
            # Skip categorised examples
            if path.parent.name in category_indices:
                continue
            examples.append(Example(path.parent))

    return examples


def create_nested_structures(examples: list[Example]) -> dict[str, dict[str, dict[str, dict[str, NestedStructure]]]]:
    """Create nested structures for training and distillation categories."""
    nested_structures: dict[str, dict[str, dict[str, dict[str, NestedStructure]]]] = {}

    # Map category names to actual directory names
    category_dir_mapping = {
        "distillation": "distill",
    }

    for example in examples:
        if example.category not in ["training", "distillation"]:
            continue

        # Use mapped directory name if available
        dir_name = category_dir_mapping.get(example.category, example.category)
        category_dir = EXAMPLE_DIR / dir_name
        relative_path = example.path.relative_to(category_dir)
        path_parts = relative_path.parts

        if example.category == "training":
            # For training examples like finetune/wan_i2v_14b_480p/crush_smol
            if len(path_parts) >= 3:
                method = path_parts[0]  # e.g., "finetune"
                model = path_parts[1]  # e.g., "wan_i2v_14b_480p"
                dataset = path_parts[2]  # e.g., "crush_smol"

                # Initialize nested structure
                if example.category not in nested_structures:
                    nested_structures[example.category] = {}
                if method not in nested_structures[example.category]:
                    nested_structures[example.category][method] = {}
                if model not in nested_structures[example.category][method]:
                    nested_structures[example.category][method][model] = {}

                # Store the nested structure
                nested_structures[example.category][method][model][dataset] = NestedStructure(category=example.category,
                                                                                              method=method,
                                                                                              model=model,
                                                                                              dataset=dataset,
                                                                                              example=example)

        elif example.category == "distillation" and len(path_parts) >= 2:
            # For distillation examples like Wan2.1-T2V/Wan-Syn-Data-480P
            model = path_parts[0]  # e.g., "Wan2.1-T2V"
            dataset = path_parts[1]  # e.g., "Wan-Syn-Data-480P"
            method = "DMD"  # Default method for distillation

            # Initialize nested structure
            if example.category not in nested_structures:
                nested_structures[example.category] = {}
            if method not in nested_structures[example.category]:
                nested_structures[example.category][method] = {}
            if model not in nested_structures[example.category][method]:
                nested_structures[example.category][method][model] = {}

            # Store the nested structure
            nested_structures[example.category][method][model][dataset] = NestedStructure(category=example.category,
                                                                                          method=method,
                                                                                          model=model,
                                                                                          dataset=dataset,
                                                                                          example=example)

    return nested_structures


def generate_flat_examples(examples: list[Example], category_indices: dict[str, Index], examples_index: Index | None,
                           generate_main_index: bool) -> None:
    """Generate documentation for flat structure examples (inference, etc.)."""
    for example in examples:
        if example.category in ["training", "distillation"]:
            continue  # Skip nested structure examples

        # Determine which index to use for this example
        if example.category is not None and example.category in category_indices:
            index = category_indices[example.category]
        elif generate_main_index:
            assert examples_index is not None
            index = examples_index
        else:
            continue

        # Generate the example documentation
        doc_path = index.path.parent / f"{example.path.stem}.md"
        with open(doc_path, "w+") as f:
            f.write(example.generate())
        index.documents.append(example.path.stem)


def generate_nested_examples(nested_structures: dict[str, dict[str, dict[str, dict[str, NestedStructure]]]],
                             category_indices: dict[str, Index]) -> None:
    """Generate documentation for nested structure examples (training, distillation)."""
    for category_name in ["training", "distillation"]:
        if category_name not in category_indices or category_name not in nested_structures:
            continue

        category_index = category_indices[category_name]
        category_base_dir = category_index.path.parent

        for method, models in nested_structures[category_name].items():
            # Create method-level index
            method_index = Index(path=category_base_dir / f"{method}.md",
                                 title=fix_case(method),
                                 description=f"Examples using {method}.",
                                 caption=f"{fix_case(method)} Examples",
                                 maxdepth=2)

            for model, datasets in models.items():
                # Generate dataset examples using the Example class
                for dataset, nested_struct in datasets.items():
                    doc_path = category_base_dir / f"{nested_struct.filename}.md"
                    with open(doc_path, "w+") as f:
                        f.write(nested_struct.example.generate())

                # Create model-level index
                model_index = Index(path=category_base_dir / f"{model}.md",
                                    title=fix_case(model.replace('_', ' ')),
                                    description=f"Examples for the {model} model.",
                                    caption=f"{fix_case(model.replace('_', ' '))} Datasets",
                                    maxdepth=1)

                # Add dataset indices to model index
                for dataset, nested_struct in datasets.items():
                    model_index.documents.append(nested_struct.filename)

                # Write model index
                with open(model_index.path, "w+") as f:
                    f.write(model_index.generate())

                # Add model to method index
                method_index.documents.append(model)

            # Write method index
            with open(method_index.path, "w+") as f:
                f.write(method_index.generate())

            # Add method to main category index
            category_index.documents.append(method)


def generate_examples(generate_main_index: bool = False) -> None:
    """
    Generate example documentation.
    
    Args:
        generate_main_index (bool): Whether to generate the main examples index.
            If False, only category-specific indices will be generated.
    """
    # Create category indices
    category_indices = create_category_indices()

    # Create the main examples index only if requested
    examples_index = None
    if generate_main_index:
        main_index_dir = ROOT_DIR / "docs/examples"
        examples_index = Index(
            path=main_index_dir / "examples_index.md",
            title="💡 Examples",
            description="A collection of examples demonstrating usage of FastVideo.\n\n"
            f"All documented examples are autogenerated using [generate_examples.py](https://github.com/{GITHUB_REPO}/blob/main/docs/generate_examples.py) "
            f"from examples found in the [examples](https://github.com/{GITHUB_REPO}/tree/main/examples) directory.",
            caption="Examples",
            maxdepth=2)

    # Find all examples
    examples = find_examples(category_indices, generate_main_index)

    # Create nested structures for training and distillation
    nested_structures = create_nested_structures(examples)

    # Generate flat structure examples (inference, etc.)
    generate_flat_examples(examples, category_indices, examples_index, generate_main_index)

    # Generate nested structure examples (training, distillation)
    generate_nested_examples(nested_structures, category_indices)

    # Generate the index files for categories
    for category_index in category_indices.values():
        if category_index.documents:
            # Add to main index if it exists
            if generate_main_index and examples_index:
                main_index_dir = examples_index.path.parent
                rel_path = os.path.relpath(category_index.path, start=main_index_dir)
                examples_index.documents.insert(0, str(rel_path).replace("\\", "/").replace(".md", ""))

            # Write the category index file
            with open(category_index.path, "w+") as f:
                f.write(category_index.generate())

    # Write the main index file if requested
    if generate_main_index and examples_index:
        with open(examples_index.path, "w+") as f:
            f.write(examples_index.generate())


def on_pre_build(config, **kwargs):
    """
    MkDocs hook to generate examples before building the documentation.
    This function is called automatically by MkDocs' native hook system.
    """
    print("Generating example documentation...")
    generate_examples(generate_main_index=True)
    print("Example documentation generated successfully!")


def on_page_context(context, page, **kwargs):
    """Hide repository edit actions for pages that only exist at build time."""
    if page.file.src_uri.startswith(GENERATED_DOC_PREFIXES):
        page.edit_url = None
    return context


if __name__ == "__main__":
    print("Generating example documentation...")
    generate_examples(generate_main_index=True)
    print("Example documentation generated successfully!")