from __future__ import annotations

from typing import Any

import simpy

from kernbench.common.types import Completion, RequestHandle, Trace
import kernbench.components.builtin  # noqa: F401 — registers built-in implementations
from kernbench.components.base import ComponentBase, ComponentRegistry
from kernbench.components.context import ComponentContext
from kernbench.policy.address.phyaddr import PhysAddr
from kernbench.policy.routing.router import AddressResolver, PathRouter
from kernbench.runtime_api.kernel import KernelLaunchMsg, MemoryReadMsg, MemoryWriteMsg, PeDmaMsg
from kernbench.sim_engine.transaction import Transaction
from kernbench.topology.types import Edge, TopologyGraph


class GraphEngine:
    """simpy-based discrete-event simulation engine.

    Request routing:
      MemoryWrite/Read: pcie_ep → io_noc → cube → router mesh → hbm_ctrl (m_cpu bypass)
      KernelLaunch:     pcie_ep → io_noc → io_cpu → io_noc → cube → m_cpu → PE
      PeDmaMsg:         pe_dma → router mesh → hbm_ctrl (direct probe)

    Component implementations are DI-injectable via component_overrides (ADR-0007 D3).
    """

    def __init__(
        self,
        graph: TopologyGraph,
        *,
        component_overrides: dict[str, type[ComponentBase]] | None = None,
        enable_data: bool = False,
    ) -> None:
        self._env = simpy.Environment()
        self._resolver = AddressResolver(graph)
        self._router = PathRouter(graph)
        self._nodes = graph.nodes
        self._edge_map: dict[tuple[str, str], Edge] = {}
        for e in graph.edges:
            self._edge_map[(e.src, e.dst)] = e
        self._ns_per_mm: float = graph.spec.get("system", {}).get("ns_per_mm", 0.01)
        self._results: dict[str, tuple[Completion, Trace]] = {}
        self._events: dict[str, simpy.Event] = {}
        self._counter = 0
        overrides = component_overrides or {}
        # ADR-0020: optional data execution support
        self._op_logger = None
        self._memory_store = None
        if enable_data:
            from kernbench.sim_engine.memory_store import MemoryStore
            from kernbench.sim_engine.op_log import OpLogger
            self._op_logger = OpLogger()
            self._memory_store = MemoryStore()

        ctx = ComponentContext(
            router=self._router,
            resolver=self._resolver,
            positions={nid: n.pos_mm for nid, n in graph.nodes.items()},
            ns_per_mm=self._ns_per_mm,
            edge_map=self._edge_map,
            spec=graph.spec,
            memory_store=self._memory_store,
            op_logger=self._op_logger,
        )
        self._components: dict[str, ComponentBase] = {
            node_id: ComponentRegistry.create(node, overrides, ctx)
            for node_id, node in graph.nodes.items()
        }

        # Wire ports: one Store per directed edge (ADR-0015 D1)
        for e in graph.edges:
            src_comp = self._components.get(e.src)
            dst_comp = self._components.get(e.dst)
            if src_comp is None or dst_comp is None:
                continue
            store: simpy.Store = simpy.Store(self._env)
            src_comp.out_ports[e.dst] = store
            dst_comp.in_ports[e.src] = store

        # Wire processes: propagation delay + BW occupancy per edge (ADR-0015 D2)
        # Cut-through (wormhole) model: wires apply propagation delay per hop.
        # BW occupancy (available_at) tracks when each directed link becomes free
        # for the next transaction, modeling back-to-back serialization contention.
        for e in graph.edges:
            src_comp = self._components.get(e.src)
            dst_comp = self._components.get(e.dst)
            if src_comp is None or dst_comp is None:
                continue
            prop_ns = e.distance_mm * self._ns_per_mm
            bw_gbs = e.bw_gbs or 0.0
            self._env.process(
                self._wire(src_comp.out_ports[e.dst], dst_comp.in_ports[e.src],
                           prop_ns, bw_gbs)
            )

        # Attach host queues to PCIE_EP in_ports before start() (ADR-0015 D3)
        self._host_queues: dict[str, simpy.Store] = {}
        for pcie_ep_id in self._resolver.find_all_pcie_eps():
            host_q: simpy.Store = simpy.Store(self._env)
            self._components[pcie_ep_id].in_ports["host"] = host_q
            self._host_queues[pcie_ep_id] = host_q

        # Attach host queues to PE_DMA nodes for direct PE DMA injection
        self._pe_dma_queues: dict[str, simpy.Store] = {}
        for node_id, node in graph.nodes.items():
            if node.kind == "pe_dma":
                host_q = simpy.Store(self._env)
                self._components[node_id].in_ports["host"] = host_q
                self._pe_dma_queues[node_id] = host_q

        # Wire PE_DMA._mmu to PE_MMU's underlying PeMMU utility object
        for node_id, node in graph.nodes.items():
            if node.kind == "pe_dma":
                # Derive PE_MMU node ID from PE_DMA node ID
                pe_prefix = node_id.rsplit(".", 1)[0]  # e.g. "sip0.cube0.pe0"
                mmu_id = f"{pe_prefix}.pe_mmu"
                mmu_comp = self._components.get(mmu_id)
                if mmu_comp is not None and hasattr(mmu_comp, "mmu"):
                    self._components[node_id]._mmu = mmu_comp.mmu

        # Inject op_logger into all components (ADR-0020 D2)
        if self._op_logger:
            for comp in self._components.values():
                comp._op_logger = self._op_logger

        # Start components after all ports are wired (ADR-0015 D3)
        for comp in self._components.values():
            comp.start(self._env)

    @property
    def op_log(self):
        """Op log records from Phase 1 (ADR-0020)."""
        return self._op_logger.records if self._op_logger else []

    @property
    def memory_store(self):
        """MemoryStore from Phase 1 (ADR-0020)."""
        return self._memory_store

    def submit(self, request: Any) -> RequestHandle:
        self._counter += 1
        handle = RequestHandle(f"h{self._counter}")
        event = self._env.event()
        self._events[str(handle)] = event
        self._env.process(self._process(str(handle), request, event))
        return handle

    def wait(self, handle: RequestHandle) -> None:
        key = str(handle)
        event = self._events[key]
        if not event.triggered:
            self._env.run(until=event)

    def get_completion(self, handle: RequestHandle) -> tuple[Completion, Trace | None]:
        return self._results[str(handle)]

    def mmu_map(self, va: int, pa: int, size: int) -> None:
        """Sideband: install VA→PA mapping in all PE_MMU components."""
        for node_id, comp in self._components.items():
            if hasattr(comp, "mmu"):
                comp.mmu.map(va=va, pa=pa, size=size)

    def mmu_map_pe(
        self, sip: int, cube: int, pe: int, va: int, pa: int, size: int,
    ) -> None:
        """Sideband: install VA→PA mapping in a specific PE's MMU only."""
        mmu_id = f"sip{sip}.cube{cube}.pe{pe}.pe_mmu"
        comp = self._components.get(mmu_id)
        if comp is not None and hasattr(comp, "mmu"):
            comp.mmu.map(va=va, pa=pa, size=size)

    def mmu_unmap(self, va: int, size: int) -> None:
        """Sideband: remove VA mapping from all PE_MMU components."""
        for node_id, comp in self._components.items():
            if hasattr(comp, "mmu"):
                comp.mmu.unmap(va=va, size=size)

    # ── internal ────────────────────────────────────────────────────

    def _wire(
        self,
        out_port: simpy.Store,
        in_port: simpy.Store,
        prop_ns: float,
        bw_gbs: float = 0.0,
    ):
        """SimPy process: relay messages with propagation delay and BW occupancy.

        Each directed edge maintains an ``available_at`` timestamp tracking when
        the link becomes free for the next transaction.  When a transaction of
        ``nbytes`` uses a link with ``bw_gbs``, the link is occupied for
        ``nbytes / bw_gbs`` ns.  The *next* transaction on the same directed
        link must wait until ``available_at`` passes (back-to-back serialization).

        The *current* transaction is NOT delayed by its own occupancy — only by
        a prior transaction's occupancy that has not yet cleared.  This avoids
        double-drain: terminal drain_ns handles single-transaction serialization,
        while available_at handles inter-transaction BW contention.
        """
        available_at = 0.0
        while True:
            msg = yield out_port.get()
            # BW occupancy: wait for link to become free, then mark busy
            if bw_gbs > 0:
                nbytes = getattr(msg, "nbytes", 0)
                if nbytes > 0:
                    wait = available_at - self._env.now
                    if wait > 0:
                        yield self._env.timeout(wait)
                    available_at = self._env.now + (nbytes / bw_gbs)
            # Propagation delay
            if prop_ns > 0:
                yield self._env.timeout(prop_ns)
            yield in_port.put(msg)

    def _process(self, key: str, request: Any, done: simpy.Event):
        if isinstance(request, PeDmaMsg):
            yield from self._process_pe_dma(key, request, done)
            return

        if isinstance(request, (MemoryWriteMsg, MemoryReadMsg)):
            yield from self._process_memory_direct(key, request, done)
            return

        from kernbench.runtime_api.kernel import MmuMapMsg, MmuUnmapMsg
        if isinstance(request, (MmuMapMsg, MmuUnmapMsg)):
            yield from self._process_mmu_msg(key, request, done)
            return

        entries = self._entry_points(request)
        if not entries:
            self._results[key] = (
                Completion(ok=True),
                {"total_ns": 0.0, "nbytes": 0},
            )
            done.succeed()
            return

        start_ns = self._env.now
        total_nbytes = 0

        root_txn: Transaction | None = None
        if len(entries) == 1:
            # Single-SIP: direct inject (common path, no extra events)
            pcie_ep_id, io_cpu_id, nbytes = entries[0]
            total_nbytes = nbytes
            path = self._router.find_node_path(pcie_ep_id, io_cpu_id)
            txn_done = self._env.event()
            txn = Transaction(request=request, path=path, step=0, nbytes=nbytes, done=txn_done)
            root_txn = txn
            yield self._host_queues[pcie_ep_id].put(txn)
            yield txn_done
        else:
            # Multi-SIP: inject per SIP, aggregate completions (ADR-0007)
            sub_dones: list[simpy.Event] = []
            sub_txns: list[Transaction] = []
            for pcie_ep_id, io_cpu_id, nbytes in entries:
                total_nbytes = max(total_nbytes, nbytes)
                path = self._router.find_node_path(pcie_ep_id, io_cpu_id)
                txn_done = self._env.event()
                txn = Transaction(
                    request=request, path=path, step=0,
                    nbytes=nbytes, done=txn_done,
                )
                yield self._host_queues[pcie_ep_id].put(txn)
                sub_dones.append(txn_done)
                sub_txns.append(txn)
            for sd in sub_dones:
                yield sd
            # Aggregate pe_exec_ns from multi-SIP (max)
            pe_vals = [st.result_data.get("pe_exec_ns") for st in sub_txns]
            pe_vals = [v for v in pe_vals if v is not None]
            if pe_vals:
                if root_txn is None:
                    root_txn = sub_txns[0]
                root_txn.result_data["pe_exec_ns"] = max(pe_vals)

        total_ns = self._env.now - start_ns
        result_trace: dict[str, Any] = {"total_ns": total_ns, "nbytes": total_nbytes}
        if root_txn is not None and root_txn.result_data:
            result_trace.update(root_txn.result_data)
        self._results[key] = (
            Completion(ok=True),
            result_trace,
        )
        done.succeed()

    def _process_memory_direct(self, key: str, request: Any, done: simpy.Event):
        """Direct memory path: pcie_ep → io_noc → cube → router mesh → hbm_ctrl.

        MemoryWrite: data flows forward (nbytes on wires), drain at hbm_ctrl terminal.
        MemoryRead: command flows forward (nbytes=0), hbm_ctrl sends data back on
                    reverse path with nbytes=request.nbytes.
        """
        if isinstance(request, MemoryWriteMsg):
            sip, pa_val = request.dst_sip, request.dst_pa
        else:
            sip, pa_val = request.src_sip, request.src_pa

        pcie_ep_id = self._resolver.find_pcie_ep(sip)
        pa = PhysAddr.decode(pa_val)
        hbm_node = self._resolver.resolve(pa)
        path = self._router.find_memory_path(pcie_ep_id, hbm_node)
        drain_ns = self._path_drain_ns(path, request.nbytes)

        start_ns = self._env.now
        txn_done = self._env.event()

        is_write = isinstance(request, MemoryWriteMsg)
        txn = Transaction(
            request=request, path=path, step=0,
            nbytes=request.nbytes if is_write else 0,
            done=txn_done, drain_ns=drain_ns,
        )

        yield self._host_queues[pcie_ep_id].put(txn)
        yield txn_done

        total_ns = self._env.now - start_ns
        self._results[key] = (
            Completion(ok=True),
            {"total_ns": total_ns, "nbytes": request.nbytes},
        )
        done.succeed()

    def _process_pe_dma(self, key: str, request: PeDmaMsg, done: simpy.Event):
        """Inject a Transaction directly at PE_DMA for PE→HBM latency measurement."""
        pe_prefix = f"sip{request.src_sip}.cube{request.src_cube}.pe{request.src_pe}"
        pe_dma_id = f"{pe_prefix}.pe_dma"
        pa = PhysAddr.decode(request.dst_pa)
        dst_node = self._resolver.resolve(pa)
        path = self._router.find_path(pe_prefix, dst_node)
        drain_ns = self._path_drain_ns(path, request.nbytes)

        start_ns = self._env.now
        txn_done = self._env.event()
        txn = Transaction(request=request, path=path, step=0, nbytes=request.nbytes,
                          done=txn_done, drain_ns=drain_ns)
        yield self._pe_dma_queues[pe_dma_id].put(txn)
        yield txn_done
        total_ns = self._env.now - start_ns
        formula_ns = self._formula_latency(path, request.nbytes)
        self._results[key] = (
            Completion(ok=True),
            {"total_ns": total_ns, "formula_ns": formula_ns, "nbytes": request.nbytes},
        )
        done.succeed()

    def _path_drain_ns(self, path: list[str], nbytes: int) -> float:
        """Wormhole drain time: nbytes / bottleneck_bw along path."""
        min_bw = float("inf")
        for i in range(len(path) - 1):
            edge = self._edge_map.get((path[i], path[i + 1]))
            if edge and edge.bw_gbs:
                min_bw = min(min_bw, edge.bw_gbs)
        if min_bw == float("inf"):
            return 0.0
        return nbytes / min_bw

    def _formula_latency(self, path: list[str], nbytes: int) -> float:
        """Lower-bound formula latency (ADR-0015 D7).

        formula = Σ(wire propagation) + Σ(component overhead_ns) + drain_ns

        Phase 0: formula == actual (no contention).
        Phase 1+: formula <= actual (contention adds queueing).
        """
        total = 0.0
        # Wire propagation delays
        for i in range(len(path) - 1):
            edge = self._edge_map.get((path[i], path[i + 1]))
            if edge:
                total += edge.distance_mm * self._ns_per_mm
        # Component overhead_ns
        for node_id in path:
            node = self._nodes.get(node_id)
            if node:
                total += float(node.attrs.get("overhead_ns", 0.0))
        # Drain
        total += self._path_drain_ns(path, nbytes)
        return total

    def _entry_points(self, request: Any) -> list[tuple[str, str, int]]:
        """Return list of (pcie_ep_id, io_cpu_id, nbytes) per target SIP.

        Only handles KernelLaunchMsg. MemoryWrite/Read use _process_memory_direct.
        """
        if isinstance(request, KernelLaunchMsg):
            seen: set[int] = set()
            entries: list[tuple[str, str, int]] = []
            for arg in request.args:
                if arg.arg_kind != "tensor":
                    continue
                for shard in arg.shards:
                    if shard.sip not in seen:
                        seen.add(shard.sip)
                        entries.append((
                            self._resolver.find_pcie_ep(shard.sip),
                            self._resolver.find_io_cpu(shard.sip),
                            shard.nbytes,
                        ))
            return entries

        raise ValueError(f"unsupported request type: {type(request)}")

    def _process_mmu_msg(self, key: str, request: Any, done: simpy.Event):
        """Route MmuMapMsg/MmuUnmapMsg through fabric like KernelLaunchMsg.

        Path: Host → PCIE_EP → IO_NOC → IO_CPU → (fan-out) → M_CPU → (fan-out) → PE_MMU
        """
        start_ns = self._env.now
        target_sips = getattr(request, "target_sips", "all")

        # Determine target SIPs
        sip_set: set[int] = set()
        if target_sips == "all":
            for ep_id in self._resolver.find_all_pcie_eps():
                sip_id = int(ep_id.split(".")[0].replace("sip", ""))
                sip_set.add(sip_id)
        else:
            sip_set = set(target_sips)

        entries = []
        for sip_id in sorted(sip_set):
            entries.append((
                self._resolver.find_pcie_ep(sip_id),
                self._resolver.find_io_cpu(sip_id),
                0,  # MmuMapMsg has no data payload
            ))

        if not entries:
            self._results[key] = (Completion(ok=True), {"total_ns": 0.0})
            done.succeed()
            return

        if len(entries) == 1:
            pcie_ep_id, io_cpu_id, _ = entries[0]
            path = self._router.find_node_path(pcie_ep_id, io_cpu_id)
            txn_done = self._env.event()
            txn = Transaction(request=request, path=path, step=0, nbytes=0, done=txn_done)
            yield self._host_queues[pcie_ep_id].put(txn)
            yield txn_done
        else:
            # Multi-SIP fan-out
            sub_dones = []
            for pcie_ep_id, io_cpu_id, _ in entries:
                path = self._router.find_node_path(pcie_ep_id, io_cpu_id)
                sub_done = self._env.event()
                sub_txn = Transaction(request=request, path=path, step=0, nbytes=0, done=sub_done)
                yield self._host_queues[pcie_ep_id].put(sub_txn)
                sub_dones.append(sub_done)
            for sd in sub_dones:
                yield sd

        elapsed = self._env.now - start_ns
        self._results[key] = (
            Completion(ok=True),
            {"total_ns": elapsed, "msg_type": request.msg_type},
        )
        done.succeed()