"""Block Kit builders for the daily summary post and the 3rd-escalation alert.

Two push surfaces, no App Home (see CLAUDE.md "Slack surfaces"):
  - daily summary: header, vs-yesterday deltas, escalation + action/routine
    fields, top sites, mismatch callout, and a Open dashboard link button to
    Grafana. Long WO lists go in modals, never the channel (<100-block limit).
  - 3rd-escalation alert: standalone, batched, one @here — suppressed entirely
    on zero-3rd days (return None).

Owned by the slack-blockkit-designer agent; built in Phase 4 (docs/BUILD.md).

Slack constraints enforced here:
  - Message / modal max 100 blocks.
  - Actions block max 25 elements (kept to 5 per block for readability).
  - section text max 3000 chars.
  - Header text max 150 chars.
  - No APM deep-links anywhere — Grafana only.
"""

from __future__ import annotations

# ---------------------------------------------------------------------------
# Constants
# ---------------------------------------------------------------------------

ESCALATION_CATEGORIES: tuple[str, ...] = (
    "1st Escalation",
    "2nd Escalation",
    "3rd Escalation",
    "SIM Ticket",
    "Other Escalation",
)

# Categories that drive the "drill" buttons — non-routine and worth calling out.
# Order determines button priority when we cap at 5 per actions block.
DRILL_CATEGORY_PRIORITY: tuple[str, ...] = (
    "3rd Escalation",
    "2nd Escalation",
    "1st Escalation",
    "SIM Ticket",
    "Vendor No-Show",
    "Awaiting Scheduling",
    "Report / Docs Needed",
    "Awaiting Report / Invoice",
    "Awaiting Vendor / Parts",
    "Status Inquiry",
    "Other Escalation",
)

# Max WOs to render inline before the "+M more" overflow note in the alert.
ALERT_MAX_WOS = 20

# Max blocks reserved for WO rows in the modal (leaves headroom for
# title/footer blocks). Each WO gets 1 section block.
MODAL_HEADER_BLOCKS = 1  # title is not a block; we add 1 context block as preamble
MODAL_FOOTER_BLOCKS = 1  # overflow context block (may not be emitted)
MODAL_MAX_WO_BLOCKS = 100 - MODAL_HEADER_BLOCKS - MODAL_FOOTER_BLOCKS  # = 98


# ---------------------------------------------------------------------------
# Helpers
# ---------------------------------------------------------------------------


def _divider() -> dict:
    return {"type": "divider"}


def _header(text: str) -> dict:
    # Header block text is plain_text, max 150 chars.
    return {
        "type": "header",
        "text": {"type": "plain_text", "text": text[:150], "emoji": True},
    }


def _section(text: str) -> dict:
    # Section text is mrkdwn, max 3000 chars.
    return {
        "type": "section",
        "text": {"type": "mrkdwn", "text": text[:3000]},
    }


def _context(text: str) -> dict:
    return {
        "type": "context",
        "elements": [{"type": "mrkdwn", "text": text[:3000]}],
    }


def _fields_section(fields: list[str]) -> dict:
    """Section with up to 10 fields (Slack limit), each <=2000 chars."""
    return {
        "type": "section",
        "fields": [{"type": "mrkdwn", "text": f[:2000]} for f in fields[:10]],
    }


def _button(text: str, action_id: str, value: str) -> dict:
    """Interactive button (opens modal via interactivity handler)."""
    return {
        "type": "button",
        "text": {"type": "plain_text", "text": text, "emoji": False},
        "action_id": action_id,
        "value": value,
    }


def _link_button(text: str, url: str) -> dict:
    """Link button — opens URL directly, no action_id."""
    return {
        "type": "button",
        "text": {"type": "plain_text", "text": text, "emoji": True},
        "url": url,
    }


def _actions(elements: list[dict]) -> dict:
    """Actions block; Slack limit 25 elements, we keep <=5 per block."""
    return {"type": "actions", "elements": elements[:25]}


def _delta_str(now: int, prev: int) -> str:
    """Format a vs-yesterday delta as ▲+N or ▼-N or ~0."""
    diff = now - prev
    if diff > 0:
        return f"▲+{diff}"
    if diff < 0:
        return f"▼{diff}"
    return "~0"


def _fmt_date(dt: str) -> str:
    """Format 'YYYY-MM-DD' as 'May 28, 2026' for display."""
    try:
        from datetime import date

        d = date.fromisoformat(dt)
        # %-d is Linux-specific; strip the leading zero portably instead.
        return f"{d.strftime('%b')} {d.day}, {d.year}"
    except Exception:
        return dt


# ---------------------------------------------------------------------------
# Public surface builders
# ---------------------------------------------------------------------------


def build_daily_summary(
    today: dict,
    yesterday: dict | None,
    dashboard_url: str,
) -> list[dict]:
    """Build the daily summary post blocks.

    Returns a list of Block Kit block dicts ready to pass to ``blocks=`` in a
    ``chat.postMessage`` call. Always stays well under 100 blocks.

    Args:
        today: The contents of today's ``summary.json``.
        yesterday: The contents of yesterday's ``summary.json``, or None when
            there is no previous snapshot (first run, etc.).
        dashboard_url: The Grafana dashboard URL for the link button.
    """
    blocks: list[dict] = []

    dt = today.get("dt", "")
    date_label = _fmt_date(dt) if dt else "Today"

    # ------------------------------------------------------------------
    # 1. Header
    # ------------------------------------------------------------------
    blocks.append(_header(f"APM Work Orders — {date_label}"))

    # ------------------------------------------------------------------
    # 2. Context line: classified total + vs-yesterday deltas
    # ------------------------------------------------------------------
    classified = today.get("classified_total", 0)
    blank = today.get("blank_comment_rows", 0)
    escalation = today.get("escalation_total", 0)
    action = today.get("action_needed", 0)
    routine = today.get("routine", 0)

    if yesterday is not None:
        delta_classified = _delta_str(classified, yesterday.get("classified_total", 0))
        delta_escalation = _delta_str(escalation, yesterday.get("escalation_total", 0))
        delta_action = _delta_str(action, yesterday.get("action_needed", 0))
        context_text = (
            f"*{classified}* WOs classified ({blank} blank-comment rows excluded) "
            f"| Escalations {delta_escalation} | Action-needed {delta_action} "
            f"| vs yesterday: total {delta_classified}"
        )
    else:
        context_text = (
            f"*{classified}* WOs classified ({blank} blank-comment rows excluded) "
            f"| No prior day for delta comparison"
        )

    blocks.append(_section(context_text))
    blocks.append(_divider())

    # ------------------------------------------------------------------
    # 3. Escalation breakdown
    # ------------------------------------------------------------------
    category_counts: dict[str, int] = today.get("category_counts", {})
    third_count = today.get(
        "third_escalation_count", category_counts.get("3rd Escalation", 0)
    )

    esc_lines: list[str] = []
    for cat in ESCALATION_CATEGORIES:
        count = category_counts.get(cat, 0)
        if count == 0:
            continue
        prefix = "*" if cat == "3rd Escalation" else ""
        suffix = "*" if cat == "3rd Escalation" else ""
        esc_lines.append(f"{prefix}{cat}: {count}{suffix}")

    if esc_lines:
        blocks.append(_section("*Escalations*\n" + "\n".join(esc_lines)))
    else:
        blocks.append(_section("*Escalations*\nNone today"))

    # ------------------------------------------------------------------
    # 4. Action-needed vs routine fields
    # ------------------------------------------------------------------
    blocks.append(
        _fields_section(
            [
                f"*Action-needed*\n{action}",
                f"*Routine*\n{routine}",
                f"*3rd Escalations*\n{third_count}",
                f"*Total classified*\n{classified}",
            ]
        )
    )
    blocks.append(_divider())

    # ------------------------------------------------------------------
    # 5. Top 5 sites
    # ------------------------------------------------------------------
    top_sites: list[dict] = today.get("top_sites", [])[:5]
    if top_sites:
        site_lines = "\n".join(
            f"{i + 1}. *{s['site']}* — {s['count']} WOs"
            for i, s in enumerate(top_sites)
        )
        blocks.append(_section(f"*Top sites*\n{site_lines}"))
        blocks.append(_divider())

    # ------------------------------------------------------------------
    # 6. Mismatch callout (only when mismatches present)
    # ------------------------------------------------------------------
    mismatches: list[dict] = today.get("mismatches", [])
    if mismatches:
        mm_count = len(mismatches)
        blocks.append(
            _section(
                f":warning: *{mm_count} mismatch{'es' if mm_count != 1 else ''} "
                f"flagged* — comment intent contradicts structured state. "
                f"See the Grafana mismatch panel for details."
            )
        )
        blocks.append(_divider())

    # ------------------------------------------------------------------
    # 7. Drill buttons (action_id="drill_category") + dashboard link button
    # ------------------------------------------------------------------
    # Pick the most-common non-routine categories up to 4 slots; the 5th slot
    # is always the dashboard link button, keeping each actions block <=5.
    drill_cats: list[tuple[str, int]] = []
    for cat in DRILL_CATEGORY_PRIORITY:
        count = category_counts.get(cat, 0)
        if count > 0:
            drill_cats.append((cat, count))
        if len(drill_cats) >= 4:
            break

    button_elements: list[dict] = []
    for cat, count in drill_cats:
        short_label = cat.replace(" Escalation", " Esc.").replace("Awaiting ", "")
        short_label = short_label[:20]  # button text kept concise
        button_elements.append(
            _button(f"{short_label} ({count})", "drill_category", cat)
        )

    # Dashboard link button always present (no action_id — url button).
    button_elements.append(_link_button("Open dashboard", dashboard_url))

    blocks.append(_actions(button_elements))

    # ------------------------------------------------------------------
    # 8. Footer context
    # ------------------------------------------------------------------
    generated_at = today.get("generated_at", "")
    footer_parts = [f"Generated {generated_at}" if generated_at else ""]
    footer_parts.append(f"dt={dt}")
    blocks.append(_context(" | ".join(p for p in footer_parts if p)))

    # Safety check — should never fire in practice given the bounded sections
    # above, but surface a warning in the footer rather than silently truncate.
    if len(blocks) > 95:
        # Trim from the middle, preserve header and footer.
        over = len(blocks) - 95
        blocks = blocks[:3] + blocks[3 + over :]
        blocks.append(
            _context(f"+{over} block(s) trimmed — view full breakdown in Grafana.")
        )

    return blocks


def build_escalation_alert(escalations: list[dict]) -> list[dict] | None:
    """Build the batched 3rd-escalation alert blocks.

    Zero-3rd suppression: returns None when the list is empty. The caller must
    check for None before posting — do NOT post a message with no content.

    Args:
        escalations: Rows from ``details.json`` pre-filtered to
            ``category == "3rd Escalation"``.

    Returns:
        A list of Block Kit block dicts, or None.
    """
    if not escalations:
        return None

    blocks: list[dict] = []

    # ------------------------------------------------------------------
    # 1. Header
    # ------------------------------------------------------------------
    count = len(escalations)
    blocks.append(
        _header(f"3rd Escalation Alert — {count} WO{'s' if count != 1 else ''}")
    )

    # ------------------------------------------------------------------
    # 2. ONE @here mention (never one ping per WO)
    # ------------------------------------------------------------------
    blocks.append(
        _section(
            f"<!here> *{count} work order{'s' if count != 1 else ''} "
            f"at 3rd escalation* require immediate attention."
        )
    )
    blocks.append(_divider())

    # ------------------------------------------------------------------
    # 3. Compact WO list, capped at ALERT_MAX_WOS
    # ------------------------------------------------------------------
    visible = escalations[:ALERT_MAX_WOS]
    overflow = len(escalations) - len(visible)

    for wo in visible:
        wo_num = wo.get("wo_number", "???")
        site = wo.get("site", "—")
        desc = wo.get("wo_description", "")
        # Truncate description to keep the block tidy.
        if len(desc) > 80:
            desc = desc[:77] + "..."
        blocks.append(_section(f"*{wo_num}* — {site} — {desc}"))

    if overflow > 0:
        blocks.append(
            _context(f"+{overflow} more — see the Grafana dashboard for the full list.")
        )

    return blocks


def build_wo_modal(title: str, wos: list[dict], dashboard_url: str) -> dict:
    """Build a ``views.open`` payload (modal) listing work orders.

    Caps to Slack's 100-block modal limit by rendering the first chunk of WOs
    and appending a "+M more" overflow context block when the list is too long.
    No APM deep-links — Grafana only.

    Args:
        title: Modal title (max 24 chars enforced by Slack; truncated here).
        wos: List of per-WO dicts from ``details.json``.
        dashboard_url: The Grafana dashboard URL for the overflow note link.

    Returns:
        A dict suitable for passing to ``views.open`` as the ``view=`` arg.
    """
    # Slack enforces a 24-char modal title limit.
    title_text = title[:24]

    modal_blocks: list[dict] = []

    # Each WO is one section block. Reserve space for the optional overflow
    # context block.
    max_wo = MODAL_MAX_WO_BLOCKS - 1  # one slot reserved for potential overflow
    visible = wos[:max_wo]
    overflow_count = len(wos) - len(visible)

    for wo in visible:
        wo_num = wo.get("wo_number", "???")
        site = wo.get("site", "—")
        dept = wo.get("department", "—")
        category = wo.get("category", "—")
        snippet = wo.get("last_comment", "")
        if len(snippet) > 150:
            snippet = snippet[:147] + "..."

        text_parts = [
            f"*{wo_num}*",
            f"_{site}_ | {dept} | {category}",
        ]
        if snippet:
            text_parts.append(snippet)

        modal_blocks.append(_section("\n".join(text_parts)))

    if overflow_count > 0:
        modal_blocks.append(
            _context(
                f"+{overflow_count} more — <{dashboard_url}|view the full list in Grafana>."
            )
        )
    elif not modal_blocks:
        modal_blocks.append(_section("No work orders to display."))

    return {
        "type": "modal",
        "title": {"type": "plain_text", "text": title_text, "emoji": False},
        "close": {"type": "plain_text", "text": "Close", "emoji": False},
        "blocks": modal_blocks,
    }