import { describe, expect, it } from 'vitest';
import { CommandError } from '../../src/core/commands/Command';
import { AddNodeCommand, RemoveNodeCommand } from '../../src/core/commands/graphCommands';
import { AddPortCommand, RemovePortCommand, RenamePortCommand } from '../../src/core/commands/portCommands';
import {
  BEHAVIOR_END,
  BEHAVIOR_PARAM,
  BEHAVIOR_START,
  callProblem,
  type Graph,
  GraphInterpreter,
  portSignature,
  RUN_BEHAVIOR,
  resolveDef,
  terminalNode,
} from '../../src/core/graph';
import type { BehaviorAsset } from '../../src/core/model/Asset';
import { behaviorLookup } from '../../src/core/model/behaviorPrograms';
import { deserializeProject, serializeProject } from '../../src/core/store/serialize';
import { fakeContext, graphEditor, makeBehavior, makeProject, type ProjectFixture } from '../helpers';

/**
 * A behavior that doubles what it is given: `in1` → Multiply by 2 → `out1`, reached through its
 * start and end node. Small on purpose – what the tests are about is the call, not the arithmetic.
 */
function doubler(fixture: ProjectFixture, name = 'Double'): BehaviorAsset {
  const asset = makeBehavior(fixture, name);
  const edit = graphEditor(fixture, asset);
  const start = edit.addNode(BEHAVIOR_START);
  const end = edit.addNode(BEHAVIOR_END);
  fixture.stack.execute(new AddPortCommand(asset.id, start.id, { key: 'in1', kind: 'number' }));
  fixture.stack.execute(new AddPortCommand(asset.id, end.id, { key: 'out1', kind: 'number' }));
  const times = edit.addNode('Multiply', { b: 2 });
  edit.wire([
    [start, 'exec', end, 'exec'],
    [start, 'in1', times, 'a'],
    [times, 'result', end, 'out1'],
  ]);
  return asset;
}

/** A caller that runs `callee` on start with `input` and stores the result in its own `result` var. */
function callerOf(fixture: ProjectFixture, callee: BehaviorAsset, input: number): BehaviorAsset {
  const asset = makeBehavior(fixture, 'Caller', ['result']);
  const edit = graphEditor(fixture, asset);
  const start = edit.addNode('OnStart');
  const call = edit.addNode(RUN_BEHAVIOR, { [BEHAVIOR_PARAM]: callee.id, in1: input });
  const set = edit.variables(['result'], { write: true });
  edit.wire([
    [start, 'exec', call, 'exec'],
    [call, 'exec', set, 'exec'],
    [call, 'out1', set, 'result'],
  ]);
  return asset;
}

function runOnStart(fixture: ProjectFixture, asset: BehaviorAsset, variables: Record<string, number> = {}) {
  const interpreter = new GraphInterpreter(asset.graph, behaviorLookup(fixture.project));
  const ctx = fakeContext({ variables });
  interpreter.fire('OnStart', ctx);
  return { ctx, interpreter };
}

describe('a behavior used as a node', () => {
  it('runs the other graph in place and hands its result back', () => {
    const fixture = makeProject();
    const caller = callerOf(fixture, doubler(fixture), 21);
    expect(runOnStart(fixture, caller, { result: 0 }).ctx.variables.result).toBe(42);
  });

  it('takes its ports from the other behavior, not from its own type', () => {
    const fixture = makeProject();
    const callee = doubler(fixture);
    const caller = callerOf(fixture, callee, 1);
    const call = caller.graph.nodes.find((n) => n.type === RUN_BEHAVIOR)!;
    const def = resolveDef(call, caller.graph, behaviorLookup(fixture.project))!;
    expect(def.inputs.map((p) => p.key)).toEqual(['exec', 'in1']);
    expect(def.outputs.map((p) => p.key)).toEqual(['exec', 'out1']);
    // Named after the behavior it runs: a graph of calls is unreadable as a row of "Run behavior".
    expect(def.label).toBe('Double');
  });

  it('keeps its variables to itself: the caller’s are untouched and nothing survives the call', () => {
    const fixture = makeProject();
    const callee = makeBehavior(fixture, 'Counter', ['count']);
    const edit = graphEditor(fixture, callee);
    const start = edit.addNode(BEHAVIOR_START);
    const end = edit.addNode(BEHAVIOR_END);
    fixture.stack.execute(new AddPortCommand(callee.id, end.id, { key: 'out1', kind: 'number' }));
    const get = edit.variables(['count']);
    const plus = edit.addNode('Add', { b: 1 });
    const set = edit.variables(['count'], { write: true });
    edit.wire([
      [start, 'exec', set, 'exec'],
      [get, 'count', plus, 'a'],
      [plus, 'result', set, 'count'],
      [set, 'exec', end, 'exec'],
      [plus, 'result', end, 'out1'],
    ]);

    const caller = makeBehavior(fixture, 'Caller', ['result', 'count']);
    const cEdit = graphEditor(fixture, caller);
    const onStart = cEdit.addNode('OnStart');
    const first = cEdit.addNode(RUN_BEHAVIOR, { [BEHAVIOR_PARAM]: callee.id });
    const second = cEdit.addNode(RUN_BEHAVIOR, { [BEHAVIOR_PARAM]: callee.id });
    const store = cEdit.variables(['result'], { write: true });
    cEdit.wire([
      [onStart, 'exec', first, 'exec'],
      [first, 'exec', second, 'exec'],
      [second, 'exec', store, 'exec'],
      [second, 'out1', store, 'result'],
    ]);

    const { ctx } = runOnStart(fixture, caller, { result: 0, count: 500 });
    // 1, not 2: the second call starts from the asset default again, not from what the first left.
    expect(ctx.variables.result).toBe(1);
    // The caller has a `count` of its own – the nested run must not have written into it.
    expect(ctx.variables.count).toBe(500);
  });

  it('runs the nested graph in its own frame, so equal node ids cannot collide', () => {
    const fixture = makeProject();
    const callee = makeBehavior(fixture, 'Ninetynine');
    const cEdit = graphEditor(fixture, callee);
    const start = cEdit.addNode(BEHAVIOR_START);
    const end = cEdit.addNode(BEHAVIOR_END);
    fixture.stack.execute(new AddPortCommand(callee.id, end.id, { key: 'out1', kind: 'number' }));
    const theirs = cEdit.addNode('Number', { value: 99 });
    cEdit.wire([
      [start, 'exec', end, 'exec'],
      [theirs, 'value', end, 'out1'],
    ]);

    const caller = makeBehavior(fixture, 'Caller', ['result']);
    const edit = graphEditor(fixture, caller);
    const onStart = edit.addNode('OnStart');
    const call = edit.addNode(RUN_BEHAVIOR, { [BEHAVIOR_PARAM]: callee.id });
    const set = edit.variables(['result'], { write: true });
    const mine = edit.addNode('Number', { value: 7 });
    edit.wire([
      [onStart, 'exec', call, 'exec'],
      // Read *after* the call, and from the caller's own node – the point of the test.
      [call, 'exec', set, 'exec'],
      [mine, 'value', set, 'result'],
    ]);

    // Ids are unique in practice; forcing a collision is the only way to show the frames are real.
    // Both nodes have a `value` output, so a shared cache would hand the caller the nested 99.
    const shared = 'same-id';
    retarget(callee.graph, theirs.id, shared);
    retarget(caller.graph, mine.id, shared);
    expect(runOnStart(fixture, caller, { result: 0 }).ctx.variables.result).toBe(7);
  });

  it('refuses to run itself rather than looping forever', () => {
    const fixture = makeProject();
    const asset = doubler(fixture, 'Loop');
    const edit = graphEditor(fixture, asset);
    const start = terminalNode(asset.graph, BEHAVIOR_START)!;
    const self = edit.addNode(RUN_BEHAVIOR, { [BEHAVIOR_PARAM]: asset.id });
    edit.connect(start, 'exec', self, 'exec');
    const caller = callerOf(fixture, asset, 1);
    expect(() => runOnStart(fixture, caller, { result: 0 })).toThrow(/runs itself/);
  });

  it('a call into nothing is quiet: no behavior chosen, or one without a start node', () => {
    const fixture = makeProject();
    const empty = makeBehavior(fixture, 'Empty');
    for (const target of ['', empty.id]) {
      const caller = makeBehavior(fixture, `C${target}`, ['result']);
      const edit = graphEditor(fixture, caller);
      const start = edit.addNode('OnStart');
      const call = edit.addNode(RUN_BEHAVIOR, { [BEHAVIOR_PARAM]: target });
      const set = edit.variables(['result'], { write: true });
      edit.wire([
        [start, 'exec', call, 'exec'],
        // The flow carries on past the call, which is what keeps a dangling reference harmless.
        [call, 'exec', set, 'exec'],
      ]);
      expect(runOnStart(fixture, caller, { result: 7 }).ctx.variables.result).toBe(0);
    }
  });
});

describe('a call that cannot do anything says so', () => {
  it('names each of the four silent cases, and stays quiet about a healthy call', () => {
    const fixture = makeProject();
    const lookup = () => behaviorLookup(fixture.project);
    const callee = doubler(fixture);
    const caller = makeBehavior(fixture, 'Caller');
    const edit = graphEditor(fixture, caller);
    const call = edit.addNode(RUN_BEHAVIOR, { [BEHAVIOR_PARAM]: '' });
    const problem = () => callProblem(call, lookup(), caller.id);

    expect(problem()).toBe('No behavior picked');
    call.params[BEHAVIOR_PARAM] = caller.id;
    expect(problem()).toBe('A behavior cannot run itself');
    call.params[BEHAVIOR_PARAM] = 'gone';
    expect(problem()).toBe('That behavior is gone');
    call.params[BEHAVIOR_PARAM] = makeBehavior(fixture, 'Empty').id;
    expect(problem()).toBe('No start node – does nothing');
    call.params[BEHAVIOR_PARAM] = callee.id;
    expect(problem()).toBe(null);
    // Only a call can be dead this way; no other node type may be marked.
    expect(callProblem(edit.addNode('OnStart'), lookup(), caller.id)).toBe(null);
  });

  it('shows up in what the node view redraws on, or it would be drawn once and never again', () => {
    const fixture = makeProject();
    // A callee that declares no ports at all: losing its start node changes nothing about the
    // calling node except that it is now dead. Anything with ports would move the signature by
    // itself and prove nothing.
    const callee = makeBehavior(fixture, 'Bare');
    const start = graphEditor(fixture, callee).addNode(BEHAVIOR_START);
    const caller = makeBehavior(fixture, 'Caller');
    const call = graphEditor(fixture, caller).addNode(RUN_BEHAVIOR, { [BEHAVIOR_PARAM]: callee.id });
    const signature = () => portSignature(call, caller.graph, behaviorLookup(fixture.project), caller.id);

    const healthy = signature();
    fixture.stack.execute(new RemoveNodeCommand(callee.id, start.id));
    expect(resolveDef(call, caller.graph, behaviorLookup(fixture.project))!.label).toBe('Bare');
    expect(signature()).not.toBe(healthy);
  });

  it('without an end node the call is still a complete one: it just returns nothing', () => {
    const fixture = makeProject();
    const callee = makeBehavior(fixture, 'NoEnd');
    const cEdit = graphEditor(fixture, callee);
    const start = cEdit.addNode(BEHAVIOR_START);
    cEdit.connect(start, 'exec', cEdit.addNode('Log', { message: 'sub' }), 'exec');

    const caller = makeBehavior(fixture, 'Caller');
    const edit = graphEditor(fixture, caller);
    const onStart = edit.addNode('OnStart');
    const call = edit.addNode(RUN_BEHAVIOR, { [BEHAVIOR_PARAM]: callee.id });
    edit.wire([
      [onStart, 'exec', call, 'exec'],
      [call, 'exec', edit.addNode('Log', { message: 'after' }), 'exec'],
    ]);

    // A missing end node is not a defect, so nothing is reported.
    expect(callProblem(call, behaviorLookup(fixture.project), caller.id)).toBe(null);
    // "Done" is the nested flow running out: the sub graph is finished before the caller goes on.
    expect(runOnStart(fixture, caller).ctx.logs).toEqual(['sub', 'after']);
  });
});

describe('declared ports', () => {
  it('renaming one rewrites the edges in this graph and in every calling one', () => {
    const fixture = makeProject();
    const callee = doubler(fixture);
    const caller = callerOf(fixture, callee, 3);
    fixture.stack.execute(
      new RenamePortCommand(callee.id, terminalNode(callee.graph, BEHAVIOR_START)!.id, 'in1', 'factor'),
    );
    const start = terminalNode(callee.graph, BEHAVIOR_START)!;
    expect(start.ports).toEqual([{ key: 'factor', kind: 'number' }]);
    expect(callee.graph.edges.some((e) => e.from.port === 'factor')).toBe(true);
    // The value typed into the calling node moves with the port; losing it would be silent.
    expect(caller.graph.nodes.find((n) => n.type === RUN_BEHAVIOR)!.params).toMatchObject({ factor: 3 });
    expect(runOnStart(fixture, caller, { result: 0 }).ctx.variables.result).toBe(6);
  });

  it('a node of an unknown type is refused with a CommandError, which the editor turns into a notice', () => {
    const fixture = makeProject();
    const behavior = makeBehavior(fixture);
    const ports = [{ key: 'a', kind: 'number' as const }];
    behavior.graph.nodes.push({ id: 'n', type: 'NoSuchNode', x: 0, y: 0, params: {}, ports });
    expect(() => new RemovePortCommand(behavior.id, 'n', 'a').execute(fixture.project)).toThrow(CommandError);
  });

  it('removing one takes the edges hanging on it, in both graphs, and undo brings them back', () => {
    const fixture = makeProject();
    const callee = doubler(fixture);
    const caller = callerOf(fixture, callee, 4);
    const edgesBefore = { callee: callee.graph.edges.length, caller: caller.graph.edges.length };
    fixture.stack.execute(
      new RemovePortCommand(callee.id, terminalNode(callee.graph, BEHAVIOR_END)!.id, 'out1'),
    );
    expect(callee.graph.edges.length).toBe(edgesBefore.callee - 1);
    expect(caller.graph.edges.length).toBe(edgesBefore.caller - 1);
    fixture.stack.undo();
    expect(callee.graph.edges.length).toBe(edgesBefore.callee);
    expect(caller.graph.edges.length).toBe(edgesBefore.caller);
    expect(runOnStart(fixture, caller, { result: 0 }).ctx.variables.result).toBe(8);
  });

  it('survives saving and loading', () => {
    const fixture = makeProject();
    const callee = doubler(fixture);
    callerOf(fixture, callee, 6);
    const loaded = deserializeProject(JSON.parse(JSON.stringify(serializeProject(fixture.project))));
    const reloaded = loaded.assets.find((a) => a.id === callee.id) as BehaviorAsset;
    expect(terminalNode(reloaded.graph, BEHAVIOR_START)?.ports).toEqual([{ key: 'in1', kind: 'number' }]);
    const caller = loaded.assets.find((a) => a.name === 'Caller') as BehaviorAsset;
    const interpreter = new GraphInterpreter(caller.graph, behaviorLookup(loaded));
    const ctx = fakeContext({ variables: { result: 0 } });
    interpreter.fire('OnStart', ctx);
    expect(ctx.variables.result).toBe(12);
  });

  it('a behavior has one start and one end node, never two', () => {
    const fixture = makeProject();
    const asset = doubler(fixture);
    for (const type of [BEHAVIOR_START, BEHAVIOR_END]) {
      expect(() => fixture.stack.execute(new AddNodeCommand(asset.id, type, 0, 0))).toThrow(CommandError);
    }
  });
});

/** Gives a node a different id, edges included – used to force an id collision across graphs. */
function retarget(graph: Graph, from: string, to: string): void {
  graph.nodes.find((n) => n.id === from)!.id = to;
  for (const edge of graph.edges) {
    if (edge.from.node === from) edge.from.node = to;
    if (edge.to.node === from) edge.to.node = to;
  }
}