"""Validate public inputs before reserving GPU time; no model imports."""
from dataclasses import dataclass
import json
import math
import secrets

from config import LANGUAGES, MAX_CHARS, MAX_SEED


class InputError(ValueError):
    pass


@dataclass(frozen=True)
class SpeechRequest:
    text: str
    voice: str
    language: str
    source: str
    seed: int
    normalize: bool
    temperature: float
    top_p: float
    top_k: int
    repetition_penalty: float
    rate: float | None


def number(value, label, low, high, *, integer=False):
    if isinstance(value, bool):
        raise InputError(f"{label} must be a number.")
    try:
        result = float(value)
    except (TypeError, ValueError):
        raise InputError(f"{label} must be a number.") from None
    if not math.isfinite(result) or not low <= result <= high:
        raise InputError(f"{label} must be between {low} and {high}.")
    if integer and result != int(result):
        raise InputError(f"{label} must be a whole number.")
    return int(result) if integer else result


def validate(text, picker, source, seed, randomize, normalize, temperature, top_p, top_k,
             repetition_penalty, rate, voice_names, clip_present, consent):
    if not isinstance(text, str) or not text.strip():
        raise InputError("Write something to say first.")
    text = text.strip()
    if len(text) > MAX_CHARS:
        raise InputError(f"Use at most {MAX_CHARS} characters for one take.")
    try:
        data = json.loads(picker) if isinstance(picker, str) else picker
        voice, language = data["voice"], data["language"]
    except (ValueError, TypeError, KeyError):
        raise InputError("Choose a voice and a text language.") from None
    if not isinstance(language, str) or language not in LANGUAGES:
        raise InputError("This text language is not supported by this runtime.")
    if not isinstance(source, str) or source not in {"Preset", "Voice clip"}:
        raise InputError("Choose Preset or Voice clip.")
    if source == "Preset" and (not isinstance(voice, str) or voice not in voice_names):
        raise InputError("Choose one of the available preset voices.")
    if source == "Voice clip" and not clip_present:
        raise InputError("Upload or record a reference voice first.")
    if source == "Voice clip" and consent is not True:
        raise InputError("Confirm that you have permission to use the reference voice.")
    if not isinstance(randomize, bool) or not isinstance(normalize, bool):
        raise InputError("Seed and normalization switches must be true or false.")
    selected_seed = secrets.randbelow(MAX_SEED + 1) if randomize else number(seed, "Seed", 0, MAX_SEED, integer=True)
    rate = number(rate, "Speaking rate", 0, 30)
    return SpeechRequest(
        text, voice, language, source, selected_seed, normalize,
        number(temperature, "Temperature", .1, 1.5),
        number(top_p, "Top-p", .1, 1), number(top_k, "Top-k", 1, 400, integer=True),
        number(repetition_penalty, "Repetition penalty", 1, 4), rate if rate else None,
    )