from pydantic import BaseModel, field_validator
from datetime import datetime
from typing import Optional

# Supported models and their constraints
LYRIA_MODELS = {
    "lyria-3-clip-preview": {
        "name": "Clip Preview",
        "max_duration": 30,
        "default_duration": 30,
        "description": "30-second clip, fastest generation",
    },
    "lyria-3-pro-preview": {
        "name": "Pro",
        "max_duration": 184,
        "default_duration": 120,
        "description": "Full songs up to ~3 min, structure-aware",
    },
}

DEFAULT_MODEL = "lyria-3-clip-preview"

class GenerateRequest(BaseModel):
    prompt: str
    model: str = DEFAULT_MODEL
    duration: Optional[int] = None  # defaults to model default
    prompt_structure: Optional[dict] = None  # structured prompt fields for Pro mode

    @field_validator('model')
    @classmethod
    def validate_model(cls, v):
        v = v.strip()
        if v not in LYRIA_MODELS:
            valid = ', '.join(LYRIA_MODELS.keys())
            raise ValueError(f"Unknown model '{v}'. Supported: {valid}")
        return v

    def get_effective_duration(self) -> int:
        """Return duration clamped to model limits, defaulting to model default if not specified."""
        info = LYRIA_MODELS[self.model]
        dur = self.duration if self.duration is not None else info["default_duration"]
        return min(dur, info["max_duration"])

    def build_prompt(self) -> str:
        """Build the final prompt from structured fields or return the simple prompt."""
        if self.prompt_structure:
            parts = ["Generate a track with the following elements:"]
            field_order = [
                ("style", "Style"),
                ("timbre", "Timbre"),
                ("structure", "Structure"),
                ("mood", "Mood"),
                ("tempo", "Tempo"),
                ("instrumentation", "Instrumentation"),
                ("effects", "Effects"),
                ("additional", "Additional Notes"),
            ]
            for key, label in field_order:
                if key in self.prompt_structure and self.prompt_structure[key]:
                    parts.append(f"**{label}:** {self.prompt_structure[key]}")
            return "\n\n".join(parts)
        return self.prompt

class GenerateResponse(BaseModel):
    id: str
    status: str
    message: str

class Clip(BaseModel):
    id: str
    title: Optional[str] = None
    prompt: str
    model: str
    duration_seconds: int
    filename: str
    artwork_filename: Optional[str] = None
    file_size_bytes: Optional[int] = None
    status: str
    error_message: Optional[str] = None
    created_at: datetime
    prompt_structure: Optional[dict] = None
    bpm: Optional[float] = None
    key: Optional[str] = None
    artist: Optional[str] = None
    album: Optional[str] = None
    comment: Optional[str] = None

class RenameRequest(BaseModel):
    title: str

class MetadataRequest(BaseModel):
    artist: Optional[str] = None
    album: Optional[str] = None
    comment: Optional[str] = None

class GenerateArtworkRequest(BaseModel):
    prompt: str

class ClipList(BaseModel):
    clips: list[Clip]
    total: int