# SPDX-FileCopyrightText: 2026 James R. Barlow
# SPDX-License-Identifier: AGPL-3.0-or-later

"""Validated OCR options for the batch web interface.

The whole point of this module is that *nothing* the browser sends is ever
interpolated into a command line unchecked.  Every option is either a fixed
enum, a bounded integer, or a language code drawn from the set of language
packs actually installed in the image.
"""

from __future__ import annotations

from enum import StrEnum

from pydantic import BaseModel, ConfigDict, Field, field_validator

from webui.config import installed_languages


class Mode(StrEnum):
    """What to do about pages that already contain text."""

    normal = "normal"
    skip_text = "skip-text"
    force_ocr = "force-ocr"
    redo_ocr = "redo-ocr"


class OutputType(StrEnum):
    """Requested output conformance level."""

    pdfa = "pdfa"
    pdfa_1 = "pdfa-1"
    pdfa_2 = "pdfa-2"
    pdfa_3 = "pdfa-3"
    pdf = "pdf"


class OcrOptions(BaseModel):
    """Options applied to every file in a batch."""

    model_config = ConfigDict(extra="forbid", use_enum_values=False)

    languages: list[str] = Field(default_factory=lambda: ["eng"], max_length=8)
    mode: Mode = Mode.skip_text
    output_type: OutputType = OutputType.pdfa
    optimize: int = Field(default=1, ge=0, le=3)
    deskew: bool = False
    clean: bool = False
    rotate_pages: bool = False
    image_dpi: int = Field(default=300, ge=1, le=5000)

    @field_validator("languages")
    @classmethod
    def _known_languages(cls, value: list[str]) -> list[str]:
        if not value:
            return ["eng"]
        available = set(installed_languages())
        unknown = [lang for lang in value if lang not in available]
        if unknown:
            raise ValueError(
                "unknown or uninstalled language(s): " + ", ".join(sorted(unknown))
            )
        # Preserve caller order (Tesseract weights the first language most)
        # while dropping duplicates.
        seen: set[str] = set()
        ordered = []
        for lang in value:
            if lang not in seen:
                seen.add(lang)
                ordered.append(lang)
        return ordered

    def to_args(self, *, jobs: int, is_image: bool) -> list[str]:
        """Render these options as ``ocrmypdf`` command line arguments.

        Args:
            jobs: Value for ``--jobs``, OCRmyPDF's internal worker count.
            is_image: True when the input is an image rather than a PDF, in
                which case ``--image-dpi`` is meaningful.
        """
        args = [
            f"--language={'+'.join(self.languages)}",
            f"--output-type={self.output_type.value}",
            f"--optimize={self.optimize}",
            f"--jobs={jobs}",
        ]
        if self.mode is not Mode.normal:
            args.append(f"--{self.mode.value}")
        if self.deskew:
            args.append("--deskew")
        if self.clean:
            args.append("--clean")
        if self.rotate_pages:
            args.append("--rotate-pages")
        if is_image:
            args.append(f"--image-dpi={self.image_dpi}")
        # A soft render error on one page shouldn't sink an unattended batch.
        args.append("--continue-on-soft-render-error")
        return args