"""Session-quality filter (T01).

The capture layer ingests *every* session it finds — including API health-checks,
smoke-tests, and interrupted runs (e.g. ``llm-connect`` firing "Say hello in one
word", or a transcript that is just ``[Request interrupted by user]``). These are
not real coding work, but the outcome heuristic labels the short ones ``abandoned``
and the clusterer then mints false-positive "problem" patterns from them.

:func:`is_real_coding_session` gates those out so Detect signals/clusters form only
over genuine coding sessions. It is intentionally conservative — a session counts
as real if it shows substantive activity, and is dropped only on clear trivial
markers. Thresholds come from ``[detect.quality]`` in ``config.toml``.
"""

from __future__ import annotations

from dataclasses import dataclass
from typing import Optional

# Prompt prefixes/markers that indicate a non-coding or interrupted session.
_TRIVIAL_PROMPTS = (
    "say hello", "hello", "[request interrupted", "return only this json",
    "ping", "ok", "<system-reminder>",
)

# Tool buckets that count as "substantive" coding activity.
_SUBSTANTIVE_TOOLS = (
    "Edit", "Write", "Read", "Bash", "search_replace", "write", "read_file",
    "run_terminal_command", "grep", "Grep", "glob", "Glob", "NotebookEdit",
)


@dataclass
class QualityConfig:
    min_events: int = 20          # below this, not a real coding session
    min_substantive: int = 3      # >= this many substantive tool calls required
    min_prompt_len: int = 25      # first prompt shorter than this is suspect


def quality_config(config: Optional[dict] = None) -> QualityConfig:
    d = (config or {}).get("detect", {}).get("quality", {}) if config else {}
    return QualityConfig(
        min_events=d.get("min_events", 20),
        min_substantive=d.get("min_substantive", 3),
        min_prompt_len=d.get("min_prompt_len", 25),
    )


def _substantive_calls(digest: dict) -> int:
    hist = digest.get("tool_histogram") or {}
    return sum(n for t, n in hist.items() if t in _SUBSTANTIVE_TOOLS)


def is_real_coding_session(digest: dict, config: Optional[QualityConfig] = None) -> bool:
    cfg = config or QualityConfig()

    if not digest.get("repo"):
        return False
    if digest.get("event_count", 0) < cfg.min_events:
        return False
    if _substantive_calls(digest) < cfg.min_substantive:
        return False

    prompt = (digest.get("first_prompt") or "").strip().lower()
    if len(prompt) < cfg.min_prompt_len:
        return False
    if any(prompt.startswith(p) for p in _TRIVIAL_PROMPTS):
        return False

    return True


def filter_real(digests: list[dict], config: Optional[QualityConfig] = None) -> list[dict]:
    cfg = config or QualityConfig()
    return [d for d in digests if is_real_coding_session(d, cfg)]