export type StateTransitionDiagnostics = {
  integration?: {
    segments?: Array<{
      stateTransitionTimes?: number[];
    }>;
  };
};

type EventSeriesVariable = {
  scope: "component" | "port";
  portName: string | null;
  quantity: string;
  category: string;
};

type EventSeriesComponent = {
  data: {
    ports: Array<{
      name: string;
      domain: string;
    }>;
  };
};

const ISOLATED_EVENT_FORCE_RATIO = 100;

export function resultStateTransitionSampleIndices(
  time: number[],
  diagnostics: StateTransitionDiagnostics,
) {
  const indices = new Set<number>();
  for (const segment of diagnostics.integration?.segments ?? []) {
    for (const eventTime of segment.stateTransitionTimes ?? []) {
      if (!Number.isFinite(eventTime)) {
        continue;
      }
      let index = time.indexOf(eventTime);
      if (index < 0) {
        const tolerance = 1e-12 * Math.max(Math.abs(eventTime), 1);
        index = time.findIndex(
          (sampleTime) => Math.abs(sampleTime - eventTime) <= tolerance,
        );
      }
      if (index >= 0) {
        indices.add(index);
      }
    }
  }
  return indices;
}

export function continuousMechanicalForceChartValues(
  variable: EventSeriesVariable,
  component: EventSeriesComponent | undefined,
  values: number[],
  stateTransitionSampleIndices: ReadonlySet<number>,
) {
  const componentHasMechanicalPort = Boolean(
    component?.data.ports.some((port) => port.domain === "mechanical"),
  );
  const forceBelongsToMechanicalDomain =
    variable.scope === "component"
      ? variable.category === "derived" && componentHasMechanicalPort
      : variable.portName !== null &&
        Boolean(
          component?.data.ports.some(
            (port) =>
              port.name === variable.portName &&
              port.domain === "mechanical",
          ),
        );
  if (variable.quantity !== "force" || !forceBelongsToMechanicalDomain) {
    return { values, separatedEventSampleCount: 0 };
  }

  const isolatedEventIndices: number[] = [];
  for (const index of stateTransitionSampleIndices) {
    if (
      index < 0 ||
      index >= values.length ||
      !isolatedEventForceSample(
        values,
        index,
        stateTransitionSampleIndices,
      )
    ) {
      continue;
    }
    isolatedEventIndices.push(index);
  }
  if (isolatedEventIndices.length === 0) {
    return { values, separatedEventSampleCount: 0 };
  }

  const displayValues = values.slice();
  for (const index of isolatedEventIndices) {
    displayValues[index] = Number.NaN;
  }
  return {
    values: displayValues,
    separatedEventSampleCount: isolatedEventIndices.length,
  };
}

function isolatedEventForceSample(
  values: number[],
  index: number,
  stateTransitionSampleIndices: ReadonlySet<number>,
) {
  const value = Number(values[index]);
  if (!Number.isFinite(value)) {
    return false;
  }
  const previous = finiteNonEventNeighbor(
    values,
    index - 1,
    -1,
    stateTransitionSampleIndices,
  );
  const next = finiteNonEventNeighbor(
    values,
    index + 1,
    1,
    stateTransitionSampleIndices,
  );
  if (previous === null || next === null) {
    return false;
  }

  const localScale = Math.max(
    Math.abs(previous),
    Math.abs(next),
    Math.abs(next - previous),
    1e-9,
  );
  const localEstimate = (previous + next) / 2;
  return (
    Math.abs(value) > ISOLATED_EVENT_FORCE_RATIO * localScale &&
    Math.abs(value - localEstimate) >
      ISOLATED_EVENT_FORCE_RATIO * localScale
  );
}

function finiteNonEventNeighbor(
  values: number[],
  startIndex: number,
  direction: -1 | 1,
  stateTransitionSampleIndices: ReadonlySet<number>,
) {
  for (
    let index = startIndex;
    index >= 0 && index < values.length;
    index += direction
  ) {
    if (stateTransitionSampleIndices.has(index)) {
      continue;
    }
    const value = Number(values[index]);
    if (Number.isFinite(value)) {
      return value;
    }
  }
  return null;
}

export function segmentedChartPath(
  time: number[],
  values: number[],
  xPosition: (value: number) => number,
  yPosition: (value: number) => number,
) {
  const commands: string[] = [];
  let continuesSegment = false;
  for (let index = 0; index < time.length; index += 1) {
    const x = Number(time[index]);
    const y = Number(values[index]);
    if (!Number.isFinite(x)) {
      continuesSegment = false;
      continue;
    }
    if (!Number.isFinite(y)) {
      continue;
    }
    commands.push(
      `${continuesSegment ? "L" : "M"} ${xPosition(x).toFixed(2)} ${yPosition(y).toFixed(2)}`,
    );
    continuesSegment = true;
  }
  return commands.join(" ");
}