"""Synthetic workflow lab, implemented from usecases/generalisation-spec.md."""
from copy import deepcopy
from dataclasses import dataclass

from testdriver.actions import Surface
from testdriver.drivers import Realization


class WorkflowDriver:
    """A completed denial is a protocol response, not a failed realization."""

    surface = Surface("workflow", "direct")

    def __init__(self, lab):
        self.lab = lab

    def realize(self, actor, action):
        action.check_surface(self.surface.id)
        response = self.lab.request(actor.credentials["token"], action.name, **action.args)
        return Realization(self.surface.id, {"operation": action.name, "response": response})


class ApprovalLab:
    tokens = {"requester": "fixture-requester", "reviewer": "fixture-reviewer",
              "delegate": "fixture-delegate"}

    def __init__(self, defect=None):
        self.defect = defect
        self.state = "draft"
        self.reviewer = "reviewer"
        self.approved_by = None
        self.receipts = []

    def may_execute(self, actor):
        return actor == "requester" and (
            self.state == "approved" or self.defect == "premature-execution"
        )

    def request(self, token, operation, **args):
        actor = next((a for a, t in self.tokens.items() if t == token), None)
        allowed = False
        if operation == "submit":
            allowed = actor == "requester" and self.state == "draft"
            if allowed:
                self.state = "pending"
        elif operation == "delegate":
            allowed = (actor == self.reviewer and self.state == "pending"
                       and args["to"] == "delegate")
            if allowed:
                self.reviewer = args["to"]
        elif operation == "approve":
            allowed = self.state == "pending" and (
                actor == self.reviewer
                or (actor == "requester" and self.defect == "self-approval")
                or (actor == "reviewer" and self.defect == "stale-delegation")
            )
            if allowed:
                self.state, self.approved_by = "approved", actor
        elif operation == "execute":
            allowed = self.may_execute(actor)
            if allowed:
                self.state = "executed"
        else:
            raise ValueError(operation)
        receipt = {"actor": actor, "operation": operation, "allowed": allowed}
        self.receipts.append(receipt)
        return deepcopy(receipt)


@dataclass
class ApprovalObserver:
    lab: ApprovalLab
    name: str = "approval-observer"

    def snapshot(self):
        return deepcopy({
            "state": self.lab.state,
            "reviewer": self.lab.reviewer,
            "approved_by": self.lab.approved_by,
            "receipts": self.lab.receipts,
            "execution_gate": {actor: self.lab.may_execute(actor) for actor in self.lab.tokens},
        })


class TenantLab:
    tokens = {"admin-a": "fixture-admin-a", "admin-b": "fixture-admin-b"}
    tenants = {"admin-a": "A", "admin-b": "B"}

    def __init__(self, defect=None):
        self.defect = defect
        self.records = {}
        self.deleted = {}
        self.receipts = []

    def read(self, actor, tenant, resource):
        if self.tenants.get(actor) != tenant and self.defect != "foreign-read":
            return {"allowed": False, "content": None}
        return {"allowed": (tenant, resource) in self.records,
                "content": self.records.get((tenant, resource))}

    def request(self, token, operation, tenant, resource="R", content=None):
        actor = next((a for a, t in self.tokens.items() if t == token), None)
        allowed = self.tenants.get(actor) == tenant
        key = (tenant, resource)
        if operation == "create":
            allowed = allowed and key not in self.records
            if allowed:
                self.records[key] = (self.deleted.get(key, content)
                                     if self.defect == "resurrect-content" else content)
        elif operation == "delete":
            allowed = (allowed or self.defect == "foreign-delete") and key in self.records
            if allowed:
                self.deleted[key] = self.records.pop(key)
                if self.defect == "unscoped-delete":
                    self.records = {k: v for k, v in self.records.items() if k[1] != resource}
        else:
            raise ValueError(operation)
        receipt = {"actor": actor, "operation": operation, "tenant": tenant, "allowed": allowed}
        self.receipts.append(receipt)
        return deepcopy(receipt)


@dataclass
class TenantObserver:
    lab: TenantLab
    name: str = "tenant-observer"

    def snapshot(self):
        return deepcopy({
            "records": {tenant: self.lab.records.get((tenant, "R")) for tenant in ("A", "B")},
            "reads": {f"{actor}:{tenant}": self.lab.read(actor, tenant, "R")
                      for actor in self.lab.tokens for tenant in ("A", "B")},
            "receipts": self.lab.receipts,
        })