from typing import List, Optional

from pydantic import BaseModel, ConfigDict, Field, field_validator, model_validator


class SentenceBoundary(BaseModel):
    model_config = ConfigDict(extra="forbid")

    index: int = Field(ge=0)
    start_ms: int = Field(ge=0)
    end_ms: int = Field(gt=0)
    text: Optional[str] = None

    @model_validator(mode="after")
    def validate_range(self):
        if self.end_ms <= self.start_ms:
            raise ValueError("end_ms must be greater than start_ms")
        return self


class SentenceBoundaryDocument(BaseModel):
    model_config = ConfigDict(extra="forbid")

    video_hash: str
    duration_ms: int = Field(gt=0)
    algorithm_version: str = Field(min_length=1)
    sentences: List[SentenceBoundary]

    @field_validator("video_hash")
    @classmethod
    def validate_video_hash(cls, value: str) -> str:
        normalized = value.strip().lower()
        if len(normalized) != 64 or any(char not in "0123456789abcdef" for char in normalized):
            raise ValueError("video_hash must be a SHA-256 hex digest")
        return normalized

    @model_validator(mode="after")
    def validate_sentences(self):
        previous_end = 0
        for expected_index, sentence in enumerate(self.sentences):
            if sentence.index != expected_index:
                raise ValueError("sentence indexes must be contiguous and zero-based")
            if sentence.start_ms < previous_end:
                raise ValueError("sentences must be sorted and non-overlapping")
            if sentence.end_ms > self.duration_ms:
                raise ValueError("sentence end_ms cannot exceed duration_ms")
            previous_end = sentence.end_ms
        return self