"""PCB datasheet review prompt and layout neighborhood context (no auto-place)."""

from __future__ import annotations

import math

from backend.periscopex.functional_groups import FunctionalGroupsReport
from backend.periscopex.models import DesignGraph, LayoutGraph
from backend.periscopex.pcb_inventory import PcbInventoryReport
from backend.periscopex.si_check import net_length_mm

PCB_SYSTEM_PROMPT = """\
You are an electrical engineer reviewing a PCB layout against the IC \
datasheet. This is an EXAM of the existing board — do not propose a new \
floorplan, do not invent millimetres, and do not write Gerbers.

### Coverage checklist (layout)
- Domains (power-rail islands) and functional groups (IC + satellites: \
decoupling, bulk, filter, crystal, pullup).
- Placement: decoupling and crystal load caps vs datasheet layout notes \
and any numeric layout_rules (max_distance_mm, same_layer, thermal vias).
- Routing: net lengths, differential-pair skew, obvious stubs; length \
match only when the datasheet gives millimetres.
- Impedance: comment on Z0 only when stackup + width numbers are in the \
context. Never assume 50 Ω.
- Derating: flag a capacitor only when both operating and rated voltages \
are present and Vop exceeds Vrated.
- Filters: topology already on the schematic — check whether filter parts \
sit with the IC they serve when coordinates exist.
- Datasheet layout pages (typical application / PCB layout) vs this \
neighborhood.

### Findings
Every finding MUST have status ERROR, WARNING, or INFO and a non-empty \
recommendation (what to change on the board). INFO still needs a next \
step (e.g. "Measure Z0 after stackup is filled in").

Call submit_review. Empty findings with checked_areas is valid when the \
layout matches the datasheet.
"""


def build_pcb_layout_context(
    ic_ref: str,
    graph: DesignGraph,
    layout: LayoutGraph | None,
    plan: FunctionalGroupsReport | None,
    inventory: PcbInventoryReport | None = None,
) -> str:
    """Plain-text block appended to the schematic neighborhood for PCB review."""
    lines = ["### PCB layout context (existing board — do not move parts)"]
    domain_id = None
    group = None
    if plan is not None:
        for g in plan.groups:
            if g.ref == ic_ref:
                group = g
                break
        for d in plan.domains:
            if ic_ref in d.ic_refs:
                domain_id = d.domain_id
                lines.append(
                    f"Domain: {d.domain_id} (power nets: {', '.join(d.power_nets) or '—'})"
                )
                break
        if group is None:
            lines.append("Functional group: (this IC is not in a classified group)")
        else:
            lines.append(
                f"Functional group: {group.ref} subtype={group.component_subtype or '—'} "
                f"rank={group.rank}"
            )
            sats = group.satellites or []
            if sats:
                lines.append("Satellites:")
                for s in sats:
                    xy = ""
                    if layout and s.ref in layout.footprints:
                        fp = layout.footprints[s.ref]
                        xy = f" @ ({fp.x:.2f},{fp.y:.2f}) {fp.layer}"
                    lines.append(
                        f"  {s.ref} role={s.role_hint} nets={','.join(s.nets or [])}{xy}"
                    )
            else:
                lines.append("Satellites: none")
    if layout and ic_ref in layout.footprints:
        fp = layout.footprints[ic_ref]
        lines.append(
            f"Footprint {ic_ref}: ({fp.x:.2f},{fp.y:.2f}) layer={fp.layer} "
            f"pads={len(fp.pads)}"
        )
        near: list[str] = []
        for other, ofp in layout.footprints.items():
            if other == ic_ref:
                continue
            dist = math.hypot(ofp.x - fp.x, ofp.y - fp.y)
            if dist <= 15.0:
                near.append(f"{other} {dist:.1f}mm {ofp.layer}")
        if near:
            lines.append("Within 15 mm: " + "; ".join(sorted(near)[:24]))
        pin_nets = graph.components.get(ic_ref)
        if pin_nets:
            seen: set[str] = set()
            lines.append("Connected net lengths (PCB copper):")
            for net_name in pin_nets.pins.values():
                if not net_name or net_name in seen:
                    continue
                seen.add(net_name)
                mm = net_length_mm(layout, net_name)
                lines.append(f"  {net_name}: {mm:.2f} mm")
    elif layout is None:
        lines.append("No LayoutGraph — skip millimetre claims.")
    else:
        lines.append(f"No footprint for {ic_ref} on the PCB.")
    if inventory and inventory.nets:
        sample = inventory.nets[:12]
        lines.append("Inventory sample (name length_mm pair):")
        for n in sample:
            lines.append(
                f"  {n.name}: {n.length_mm:.2f} mm pair={n.pair or '—'} "
                f"Z0={n.z0_ohm if n.z0_ohm is not None else '—'}"
            )
    if domain_id:
        lines.append(f"(domain_id={domain_id})")
    return "\n".join(lines)