"""
Pydantic models for Metric Discovery (list_metrics) tool.

Optional match parameter is passed through to Prometheus as match[]
series selector.
"""

from datetime import datetime
from typing import Optional

from pydantic import (  # type: ignore  # pydantic in pyproject; IDE may use different interpreter
    BaseModel,
    Field,
    field_validator,
)

MAX_LIST_METRICS_LIMIT = 500


class ListMetricsRequest(BaseModel):
    """
    Input model for list_metrics requests.

    Optional match (string): regex or prefix to filter metric names.
    """

    match: Optional[str] = Field(
        default=None,
        description=(
            "Optional Prometheus series selector used as match[] "
            "(e.g. '{__name__=~\"topsql_.*\"}')."
        ),
    )
    cluster_id: str = Field(
        ...,
        description="Cluster identifier",
    )
    env: str = Field(
        ...,
        description="Environment name used in biz_type resolution (e.g. prod, staging, dev)",
    )
    deploy_type: str = Field(
        ...,
        description=(
            "Cluster deploy type used in biz_type resolution "
            "(dedicated, premium, resource_pool, starter, essential)"
        ),
    )
    limit: int = Field(
        default=MAX_LIST_METRICS_LIMIT,
        ge=1,
        le=MAX_LIST_METRICS_LIMIT,
        description=(f"Maximum number of metric names to return (1-{MAX_LIST_METRICS_LIMIT})."),
    )
    start: Optional[str] = Field(
        default=None,
        description="Optional start timestamp in RFC3339 format.",
    )
    end: Optional[str] = Field(
        default=None,
        description="Optional end timestamp in RFC3339 format.",
    )

    @field_validator("match")
    @classmethod
    def normalize_match(cls, v: Optional[str]) -> Optional[str]:
        if v is None or not v.strip():
            return None
        return v.strip()

    @field_validator("start", "end")
    @classmethod
    def validate_timestamp(cls, v: Optional[str]) -> Optional[str]:
        if v is None or not v.strip():
            return None
        value = v.strip()
        try:
            datetime.fromisoformat(value.replace("Z", "+00:00"))
            return value
        except ValueError as e:
            raise ValueError(f"Invalid timestamp format: {value}. Must be RFC3339.") from e

    @field_validator("env", "deploy_type", mode="before")
    @classmethod
    def normalize_scope_text(cls, v: str) -> str:
        return v.strip().lower()

    @field_validator("cluster_id", mode="before")
    @classmethod
    def normalize_cluster_id(cls, v: object) -> str:
        if not isinstance(v, str):
            raise ValueError("cluster_id must be a string. Quote numeric IDs explicitly.")
        return str(v).strip()