"""Normalized session schema (Tier 1) — design doc §4.

Two record kinds, ``Session`` and ``SessionEvent``, plus the small enums every
adapter targets. Field names here are the stable contract; per-flavor quirks are
absorbed inside each adapter (see design §4.3 native -> kind mapping).
"""

from __future__ import annotations

import json
from dataclasses import asdict, dataclass, field, fields
from typing import Any, Optional

SCHEMA_VERSION = 2  # v2: digest carries error_snippets (WP-0006 T01)

# Supported agent flavors. ``session_uid`` is always "<flavor>:<native id>".
FLAVORS = ("claude", "codex", "grok")

# SessionEvent.kind universe (design §4.2 / §4.3).
KINDS = (
    "user_msg",
    "assistant_msg",
    "thinking",
    "tool_call",
    "tool_result",
    "error",
    "test_run",
    "edit",
    "retry",
    "human_intervention",
    "decision",
    "lifecycle",
    "completion",
)

# Session.outcome universe.
OUTCOMES = ("success", "fail", "abandoned", "unknown")


@dataclass
class Cost:
    """Token + effort accounting for a session."""

    input_tokens: int = 0
    output_tokens: int = 0
    cache_tokens: int = 0
    wall_clock_s: float = 0.0
    turns: int = 0
    retries: int = 0


@dataclass
class Session:
    """One bounded run of a coding agent against a repo (design §4.1)."""

    session_uid: str  # "<flavor>:<native id>" — globally unique
    flavor: str
    native_session_id: str
    repo: Optional[str] = None
    domain: Optional[str] = None
    cwd: Optional[str] = None
    git_branch: Optional[str] = None
    model: Optional[str] = None
    started_at: Optional[str] = None  # ISO-8601 UTC
    ended_at: Optional[str] = None
    outcome: str = "unknown"
    cost: Cost = field(default_factory=Cost)
    task_ref: Optional[str] = None
    source_path: Optional[str] = None
    source_bytes: int = 0
    schema_version: int = SCHEMA_VERSION
    # watermarks (design §3.1): discovered -> ingested -> analyzed -> evicted
    discovered_at: Optional[str] = None
    ingested_at: Optional[str] = None
    analyzed_at: Optional[str] = None
    evicted_at: Optional[str] = None

    def __post_init__(self) -> None:
        if self.flavor not in FLAVORS:
            raise ValueError(f"unknown flavor {self.flavor!r}; expected one of {FLAVORS}")
        if self.outcome not in OUTCOMES:
            raise ValueError(f"unknown outcome {self.outcome!r}; expected one of {OUTCOMES}")
        expected_prefix = f"{self.flavor}:"
        if not self.session_uid.startswith(expected_prefix):
            raise ValueError(
                f"session_uid {self.session_uid!r} must start with {expected_prefix!r}"
            )

    @property
    def is_evictable(self) -> bool:
        """A session may be evicted from Tier 1 only once analyzed (design §3.1)."""
        return self.analyzed_at is not None and self.evicted_at is None

    @staticmethod
    def make_uid(flavor: str, native_session_id: str) -> str:
        return f"{flavor}:{native_session_id}"

    def to_dict(self) -> dict[str, Any]:
        d = asdict(self)
        return d

    def to_json(self) -> str:
        return json.dumps(self.to_dict(), sort_keys=True)

    @classmethod
    def from_dict(cls, d: dict[str, Any]) -> "Session":
        d = dict(d)
        cost = d.pop("cost", None)
        obj = cls(**{k: v for k, v in d.items() if k in _SESSION_FIELDS})
        if cost is not None:
            obj.cost = Cost(**{k: v for k, v in cost.items() if k in _COST_FIELDS})
        return obj

    @classmethod
    def from_json(cls, s: str) -> "Session":
        return cls.from_dict(json.loads(s))


@dataclass
class SessionEvent:
    """One atomic record within a session (design §4.2)."""

    session_uid: str
    seq: int  # monotonic within session
    ts: Optional[str] = None
    kind: str = "lifecycle"
    parent_seq: Optional[int] = None  # turn DAG (Claude); None for flat flavors
    role: Optional[str] = None  # user|assistant|system|tool
    tool: Optional[str] = None  # when kind in {tool_call, tool_result}
    summary: Optional[str] = None  # short, human-readable
    payload_ref: Optional[str] = None  # pointer to full body in Tier 1 blob store
    tokens: int = 0
    is_sidechain: bool = False

    def __post_init__(self) -> None:
        if self.kind not in KINDS:
            raise ValueError(f"unknown kind {self.kind!r}; expected one of {KINDS}")

    def to_dict(self) -> dict[str, Any]:
        return asdict(self)

    def to_json(self) -> str:
        return json.dumps(self.to_dict(), sort_keys=True)

    @classmethod
    def from_dict(cls, d: dict[str, Any]) -> "SessionEvent":
        return cls(**{k: v for k, v in d.items() if k in _EVENT_FIELDS})

    @classmethod
    def from_json(cls, s: str) -> "SessionEvent":
        return cls.from_dict(json.loads(s))


_SESSION_FIELDS = {f.name for f in fields(Session)}
_COST_FIELDS = {f.name for f in fields(Cost)}
_EVENT_FIELDS = {f.name for f in fields(SessionEvent)}