"""
Per-session run history — YashTech Ltd. AI Labs.

Holds every response produced in one browser session so that a second run does
not silently discard the first, and so an export can carry the whole session
rather than whichever pane happens to be on screen.

**Where this lives, and why it matters.** The log is Gradio session state:
server-side, in memory, scoped to one browser tab, and gone when that tab is
closed or reloaded. It is deliberately NOT browser storage.

A generated report can carry a patient pseudonym, a clinical indication and
findings. `localStorage` would put that on the workstation's disk, outside the
30-minute temp pruning, surviving logout, readable by any later user of that
machine, and outside anything the DPIA covers. Losing a session's history on
refresh is an inconvenience; leaving clinical text on a shared workstation is
an incident. See COMPLIANCE.md A1/A3.
"""

from __future__ import annotations

import datetime as _dt

MAX_ENTRIES = 50          # a session that runs longer than this is a new session


def append(log, *, task_id: str, task_label: str, text: str,
           question: str = "", system_prompt: str = "", now=None):
    """Return a NEW log with this run appended.

    Gradio compares state by identity for change detection, so the list is
    replaced rather than mutated — an in-place append would not propagate.
    Empty or refusal-only output is not recorded: a session history full of
    'Sign in to run tasks' is noise.
    """
    log = list(log or [])
    body = (text or "").strip()
    if not body:
        return log
    stamp = (now or _dt.datetime.now(_dt.timezone.utc)).strftime("%H:%M:%S")
    log.append({
        "n": len(log) + 1,
        "time": stamp,
        "task_id": task_id,
        "task_label": task_label or task_id,
        "question": (question or "").strip(),
        "system_prompt": (system_prompt or "").strip(),
        "text": body,
    })
    return log[-MAX_ENTRIES:]


def summary(log) -> str:
    """One line for the accordion label, so a collapsed panel still says what is in it."""
    entries = list(log or [])
    if not entries:
        return "Session history — nothing run yet"
    tasks = sorted({e["task_label"] for e in entries})
    shown = ", ".join(tasks[:3]) + (f" +{len(tasks) - 3} more" if len(tasks) > 3 else "")
    return f"Session history — {len(entries)} run(s): {shown}"


def render(log) -> str:
    """Markdown for the history panel, newest first."""
    entries = list(log or [])
    if not entries:
        return (
            "_Nothing run in this session yet._\n\n"
            "Each run is kept here so a second query does not discard the first. "
            "This history lives in the session only — it is cleared when the page "
            "is reloaded or the tab is closed, and it is never written to disk."
        )
    out = []
    for e in reversed(entries):
        out.append(f"### {e['n']}. {e['task_label']} · {e['time']} UTC")
        if e["question"]:
            out.append(f"> {e['question']}")
        out.append("")
        out.append(e["text"])
        out.append("\n---\n")
    return "\n".join(out)


def combined(log) -> str:
    """Every run in the session, oldest first, for a whole-session export."""
    entries = list(log or [])
    if not entries:
        return ""
    out = [f"_{len(entries)} run(s) in this session._", ""]
    for e in entries:
        out.append(f"## {e['n']}. {e['task_label']}")
        out.append("")
        out.append(f"- **Task:** `{e['task_id']}`")
        out.append(f"- **Run at:** {e['time']} UTC")
        if e["question"]:
            out.append(f"- **Question:** {e['question']}")
        out.append("")
        out.append(e["text"])
        if e["system_prompt"]:
            out += ["", "<details><summary>System prompt used</summary>", "",
                    f"> {e['system_prompt']}", "", "</details>"]
        out.append("\n---\n")
    return "\n".join(out)


def tasks_in(log) -> list[str]:
    return sorted({e["task_id"] for e in (log or [])})