"""The persisted shape of a flow, shared by the store, the API and the editor.

A flow is structure plus code: this module is the structure. Node logic for
``python`` nodes lives beside it as a plain ``.py`` file.
"""

from __future__ import annotations

import re
from typing import Any, Literal

from pydantic import BaseModel, ConfigDict, Field, field_validator

from fluksio.flow.messages import MessageSpec

NAME_PATTERN = re.compile(r"^[a-z][a-z0-9_]*$")


def _validate_name(value: str) -> str:
    if not NAME_PATTERN.match(value):
        raise ValueError(
            "Use lowercase letters, digits and underscores, starting with a letter"
        )
    return value


class Resources(BaseModel):
    """What one execution of a node needs to have to itself.

    Declaring nothing is the default and means what it always did: the node
    runs on the shared worker pool and nothing is accounted for it. That is
    right for the kind of node most flows are made of — a poll, a threshold, a
    message on its way somewhere.

    It is wrong for the other kind. A numerical library sizes its thread pool
    to every core it can see, so a handful of them at once oversubscribe the
    machine badly enough to starve the engine's own event loop, and a GPU
    library that preallocates most of the card deadlocks when a second one
    arrives. Both are a node saying how much of the machine it takes, which is
    what this is.
    """

    model_config = ConfigDict(extra="forbid")

    cpus: int = Field(
        default=1,
        ge=1,
        description=(
            "Cores held for the whole execution. Also what the thread-pool "
            "variables are set to, so a library sizing itself to the machine "
            "sizes itself to this instead."
        ),
    )
    gpus: int = Field(
        default=0,
        ge=0,
        description=(
            "Whole devices held for the whole execution, named to the node "
            "through CUDA_VISIBLE_DEVICES. Nothing else is given them while it "
            "runs, which is what keeps two preallocating processes apart."
        ),
    )
    env: dict[str, str] = Field(
        default_factory=dict,
        description=(
            "Extra environment for the worker this node runs in, applied over "
            "what the allocation derives. Where a library's own tuning goes — "
            "XLA_FLAGS, XLA_PYTHON_CLIENT_MEM_FRACTION — since those are "
            "composed strings the engine must not invent."
        ),
    )


class NodeDef(BaseModel):
    """A node as stored: identity, configuration and ports.

    Deliberately no canvas position. The editor lays a flow out itself, so
    where a node sits is a fact about the drawing rather than about the flow —
    and a graph nobody can arrange is one worth keeping small.
    """

    id: str
    type: str = "python"
    title: str = ""
    #: This node's settings: constants of its function, stored with the flow.
    #: A function node reads them as keyword arguments beside its ports, so a
    #: setting cannot share a name with one.
    params: dict[str, Any] = Field(default_factory=dict)
    requires: list[MessageSpec] = Field(default_factory=list)
    provides: list[MessageSpec] = Field(default_factory=list)
    #: Name of a shared source in the library, instead of this node's own file.
    #: Editing it edits the copy every flow using it runs.
    source_ref: str | None = None
    timeout: float | None = Field(
        default=None,
        ge=0,
        description=(
            "Seconds this node's code may be silent before it is stopped. A "
            "yield or an emit resets the clock, and the first call's imports "
            "are not charged to it. 0 disables the limit: the node runs until "
            "it finishes, and only a dead worker fails the call. Empty "
            "inherits the engine default."
        ),
    )
    device: str | None = Field(
        default=None,
        description=(
            "Label of the worker this node's code must run on, such as 'gpu'. "
            "Empty means the engine's own workers. A run needing a label no "
            "attached worker carries waits rather than failing."
        ),
    )
    device_policy: Literal["require", "prefer"] = Field(
        default="require",
        description=(
            "What to do when no worker carries `device`: wait for one, or run "
            "locally anyway."
        ),
    )
    cache: bool = Field(
        default=True,
        description=(
            "Whether a batch run may reuse an earlier execution of this node "
            "with the same source, settings and inputs. Turn it off for a "
            "function whose answer can change on its own."
        ),
    )
    resources: Resources | None = Field(
        default=None,
        description=(
            "What one execution of this node holds while it runs. Absent — the "
            "default — means it is not accounted for and shares the engine's "
            "workers, which is right for everything that is not compute-heavy."
        ),
    )

    @field_validator("id")
    @classmethod
    def _check_id(cls, value: str) -> str:
        return _validate_name(value)


class FlowOrigin(BaseModel):
    """Where a flow was declared, when that was somewhere other than here.

    A flow drawn on the canvas has no origin: the store is where it lives. One
    stamped with this was declared with the decorators in somebody's own
    repository and put here by ``fluksio sync``, so the node bodies below it
    are generated imports and the code they run is versioned twice — once here
    and once there. Its presence is what makes a flow code-defined.

    Deliberately no timestamp. The store commits every change it is given, so
    when a flow was last synced is a fact its own history already holds — and
    one that would otherwise change on every sync, making an unchanged upload
    look like a new version of the flow.
    """

    kind: Literal["python"] = "python"
    #: The repository root on the machine that ran ``sync``.
    repo: str = ""
    #: Its commit, and whether the tree had uncommitted changes at the time —
    #: a run stamped with a dirty commit names code that was never stored.
    commit: str = ""
    dirty: bool = False


class FlowInput(BaseModel):
    """A message the flow starts with rather than computes."""

    spec: MessageSpec
    initial: Any | None = None


class FlowDef(BaseModel):
    """One atomic flow."""

    name: str
    title: str = ""
    nodes: list[NodeDef] = Field(default_factory=list)
    inputs: list[FlowInput] = Field(default_factory=list)
    version: int = 1
    mode: Literal["live", "batch"] = Field(
        default="live",
        description=(
            "A live flow reacts to what arrives: its subscriptions, schedules "
            "and webhooks run until it is stopped. A batch flow only runs when "
            "a run asks it to, from its inputs to its outputs, and is never "
            "activated."
        ),
    )
    outputs: list[str] = Field(
        default_factory=list,
        description=(
            "Messages a batch run reports as its result, unqualified. Empty "
            "means every message the flow ends up holding."
        ),
    )
    origin: FlowOrigin | None = Field(
        default=None,
        description=(
            "Set when the flow was declared in code elsewhere and uploaded by "
            "`fluksio sync`. Absent for a flow drawn on the canvas."
        ),
    )

    @field_validator("name")
    @classmethod
    def _check_name(cls, value: str) -> str:
        return _validate_name(value)


class NodeSource(BaseModel):
    """The Python source of a node."""

    code: str
    #: True when nothing is stored and `code` is the new-node template. An
    #: editor opens on it either way; a client deciding whether somebody wrote
    #: that code needs to know it was nobody. Read-only — set on the way out.
    missing: bool = False


Health = Literal["ok", "degraded", "down"]


class NodeStatusPublic(BaseModel):
    """Whether a node loaded, and how its connection is doing."""

    id: str
    status: str = "active"
    error: str | None = None
    health: Health = "ok"
    health_detail: str | None = None
    #: The node's last runtime failure, kept after it runs again: a failure
    #: that fired an alert should leave a trace of what it was.
    last_error: str = ""
    last_error_ts: float | None = None


class MessageValue(BaseModel):
    """The last payload seen on a message."""

    value: Any = None
    ts: float | None = None


class HistoryPoint(BaseModel):
    """One numeric value a message carried, and when."""

    ts: float
    value: float


class MessageHistory(BaseModel):
    """A message's recent numeric values, oldest first.

    Only numbers are recorded, so ``numeric`` tells the panel whether an empty
    series means "nothing plottable here" or "nothing has arrived yet".
    """

    message: str
    numeric: bool = False
    points: list[HistoryPoint] = Field(default_factory=list)


class FlowSummary(BaseModel):
    name: str
    title: str = ""
    node_count: int = 0
    error_count: int = 0
    has_draft: bool = False
    enabled: bool = True
    paused: bool = False
    # Its background tasks kept crashing, so the engine stopped restarting them.
    quarantined: bool = False
    #: Of the working copy, so publishing from a list needs no second read.
    version: int = 1


class FlowsPublic(BaseModel):
    data: list[FlowSummary]
    count: int


class LibraryNode(BaseModel):
    """A node source shared across flows, and who is using it."""

    name: str
    used_by: list[str] = Field(default_factory=list)


class FlowStatePublic(BaseModel):
    values: dict[str, MessageValue] = Field(default_factory=dict)
    nodes: list[NodeStatusPublic] = Field(default_factory=list)


class ModulePackage(BaseModel):
    """One package installed in the venv node code runs on."""

    name: str
    version: str


class ModulesInfo(BaseModel):
    """The venv node code imports from, and the manifest that describes it."""

    python_version: str = ""
    venv_path: str = ""
    requirements: str = ""
    packages: list[ModulePackage] = Field(default_factory=list)
    #: Whether what is installed matches the manifest.
    applied: bool = False
    #: True when node code runs on the venv Fluksio was installed into rather
    #: than one the engine built. That venv belongs to whoever made it, so the
    #: manifest does not describe it and nothing here installs into it.
    adopted: bool = False


class ApplyRequest(BaseModel):
    """A pip manifest, one requirement per line."""

    requirements: str = ""


class ApplyResult(BaseModel):
    ok: bool
    output: str = ""


class BrainNode(BaseModel):
    """One neuron: a thing the engine talks to, or a node that only computes.

    Nodes of the same type pointing at the same outside thing — one broker
    topic, one URL, one bucket — are a single entry here, whichever flows they
    sit in. ``members`` are the ``flow.node_id`` names behind it, which is also
    what the live events are keyed by.
    """

    id: str
    label: str
    kind: str
    members: list[str] = Field(default_factory=list)
    flows: list[str] = Field(default_factory=list)
    issue: str | None = Field(
        default=None,
        description=(
            "Why this neuron cannot run, if validation found something. A "
            "failure the engine hits while running arrives over the socket "
            "instead; this is the part that is already true before anything "
            "fires, and so has to travel with the graph."
        ),
    )


class BrainEdge(BaseModel):
    """Messages carrying values from one neuron to another."""

    source: str
    target: str
    messages: list[str] = Field(default_factory=list)


class BrainGraph(BaseModel):
    """Every published flow at once, merged on what its nodes talk to."""

    nodes: list[BrainNode] = Field(default_factory=list)
    edges: list[BrainEdge] = Field(default_factory=list)


class NodeTypeInfo(BaseModel):
    """A node type the editor can offer, with its parameter schema."""

    type: str
    title: str
    description: str
    params_schema: dict[str, Any] = Field(default_factory=dict)
    has_source: bool = False
    #: Whether this type takes settings beyond the ones its schema declares.
    #: A function node's settings are its author's to name, and reach `process`
    #: as keyword arguments beside its ports.
    free_params: bool = False
    #: The package a connector came from; empty for the built-in types.
    plugin: str | None = None