"""assemble_context — the single source of truth for prompt assembly.

This pure module turns stored state (sheet JSON + daily_context + UI payload + a
windowed turn log) into the one text block — the **card** — handed to the model
each turn. It is imported by BOTH the data-generation pipeline and the live
Gradio runtime, so train/serve parity is guaranteed by *the same code running
both times*, not by discipline (DECISIONS §15, §16).

It does only stripping, simple formatting, and concatenation — **no arithmetic**
(the stat-flatten layer is gone, DECISIONS §9). Nothing ever machine-parses the
card; the model only reads it. The thing that gets parsed is the model's output.

Card layout is locked in DECISIONS §16a (normal turn) and §16b (turn-0 opening);
this module reproduces those byte-for-byte and is pinned by the golden test in
test_assemble_context.py.

Note on windowing: the turn log passed in is assumed already windowed to the last
N turns by the caller. Window size N is still open (DECISIONS §15 open items), so
it is deliberately NOT baked in here yet.
"""

# Fixed stat order — render is independent of dict insertion order (DECISIONS §3).
STAT_ORDER = ("might", "speed", "smarts", "mystique")

# resolved-branch -> the word used in a roll log tag (DECISIONS §16a).
RESULT_WORD = {"success": "succeeded", "fail": "failed"}

# Turn-0 instruction line, verbatim from DECISIONS §16b (two physical lines).
OPENING_INSTRUCTION = (
    "Create a brief, evocative, thematic description of the forest on this new day\n"
    "and how the bug experiences it, using these details:"
)


def _cap_first(text):
    """Capitalize only the first character, preserving the rest verbatim."""
    return text[:1].upper() + text[1:]


def _bug_name(bug_id):
    """Roster id -> display name: 'stag_beetle' -> 'Stag Beetle'."""
    return bug_id.replace("_", " ").title()


def render_sheet(sheet):
    """PLAYER block: header, stats, persona (DECISIONS §16a).

    Stats render exactly as stored — there is no modifier math (§9). Abilities are
    NOT listed here; the model only sees one when narrating its use (§16a).
    """
    name = _bug_name(sheet["bug"])
    hp = sheet["hp"]
    moxie = sheet["moxie"]
    header = (
        f"{name}, Level {sheet['level']} — "
        f"HP {hp['cur']}/{hp['max']} · Moxie {moxie['cur']}/{moxie['max']}"
    )
    stats = sheet["stats"]
    stat_line = " · ".join(f"{s.capitalize()} {stats[s]}" for s in STAT_ORDER)
    return f"PLAYER\n{header}\n{stat_line}\n{sheet['persona']}"


def render_day(daily_context):
    """THE WORLD block — renders on every card, not just turn 0 (DECISIONS §16a)."""
    dc = daily_context
    return (
        "THE WORLD\n"
        f"{_cap_first(dc['phase'])}, {dc['season']}. "
        f"{_cap_first(dc['weather'])}. "
        f"{_cap_first(dc['mood'])} — {dc['event']}."
    )


def render_log_entry(entry):
    """One log line. `kind` discriminates the four line shapes (DECISIONS §16a)."""
    kind = entry["kind"]
    if kind == "player":
        return f"[player] {entry['text']}"
    if kind == "player_ability":
        # Compressed marker once an ability use has scrolled into the log (§16a).
        return f"[player · used {entry['ability']}]"
    if kind == "dm":
        return f"[dm] {entry['text']}"
    if kind == "dm_roll":
        stat = entry["stat"].capitalize()
        band = entry["band"].capitalize()
        result = RESULT_WORD[entry["result"]]
        return f"[dm · {stat} check, {band}, {result}] {entry['text']}"
    raise ValueError(f"unknown log entry kind: {kind!r}")


def render_log(log):
    """WHAT JUST HAPPENED block — the windowed turn log as labeled lines."""
    lines = ["WHAT JUST HAPPENED"]
    lines.extend(render_log_entry(e) for e in log)
    return "\n".join(lines)


def render_now(user_input, sheet):
    """PLAYER'S TURN block: the declared action, plus any ability-use affordance.

    The full second-person ability `description` is surfaced here at the trigger
    moment as a narration affordance (DECISIONS §16a); it is looked up from the
    sheet so no description text rides in the UI payload.
    """
    lines = ["PLAYER'S TURN", f"[player] {user_input['message']}"]
    abilities_by_name = {a["name"]: a for a in sheet.get("abilities", [])}
    for name in user_input.get("activations", []):
        description = abilities_by_name[name]["description"]
        lines.append(f"[used ability: {name} — {description}]")
    return "\n".join(lines)


def assemble_context(
    *,
    sheet,
    daily_context,
    system_prompt,
    log=None,
    user_input=None,
    opening=False,
):
    """Assemble the full card handed to the model this turn.

    Sections are joined by blank lines. Two shapes (DECISIONS §16a/§16b):

    - normal turn: PLAYER · THE WORLD · WHAT JUST HAPPENED · PLAYER'S TURN
    - opening (turn 0, `opening=True`): PLAYER · instruction line · THE WORLD,
      with no log and no player action.

    The frozen serve system prompt is embedded verbatim as the first block; it is
    the same string in every training row and every live turn (PIPELINE-PLAN §3).
    """
    blocks = [system_prompt, render_sheet(sheet)]
    if opening:
        blocks.append(OPENING_INSTRUCTION)
        blocks.append(render_day(daily_context))
    else:
        blocks.append(render_day(daily_context))
        blocks.append(render_log(log or []))
        blocks.append(render_now(user_input, sheet))
    return "\n\n".join(blocks)