import { formatPrometheusDuration } from "../lib/formatTime";
import ASTNode, {
  VectorSelector,
  matchType,
  vectorMatchCardinality,
  nodeType,
  StartOrEnd,
  MatrixSelector,
} from "./ast";
import {
  aggregatorsWithParam,
  maybeParenthesizeBinopChild,
  escapeString,
} from "./utils";

const serializeAtAndOffset = (
  timestamp: number | null,
  startOrEnd: StartOrEnd,
  offset: number
): string =>
  `${timestamp !== null ? ` @ ${(timestamp / 1000).toFixed(3)}` : startOrEnd !== null ? ` @ ${startOrEnd}()` : ""}${
    offset === 0
      ? ""
      : offset > 0
        ? ` offset ${formatPrometheusDuration(offset)}`
        : ` offset -${formatPrometheusDuration(-offset)}`
  }`;

const serializeSelector = (node: VectorSelector | MatrixSelector): string => {
  const matchers = node.matchers
    .filter(
      (m) =>
        !(
          m.name === "__name__" &&
          m.type === matchType.equal &&
          m.value === node.name
        )
    )
    .map((m) => `${m.name}${m.type}"${escapeString(m.value)}"`);

  const range =
    node.type === nodeType.matrixSelector
      ? `[${formatPrometheusDuration(node.range)}]`
      : "";
  const atAndOffset = serializeAtAndOffset(
    node.timestamp,
    node.startOrEnd,
    node.offset
  );

  return `${node.name}${matchers.length > 0 ? `{${matchers.join(",")}}` : ""}${range}${atAndOffset}`;
};

const serializeNode = (
  node: ASTNode,
  indent = 0,
  pretty = false,
  initialIndent = true
): string => {
  const childListSeparator = pretty ? "\n" : "";
  const childSeparator = pretty ? "\n" : " ";
  const childIndent = indent + 2;
  const ind = pretty ? " ".repeat(indent) : "";
  // Needed for unary operators.
  const initialInd = initialIndent ? ind : "";

  switch (node.type) {
    case nodeType.aggregation:
      return `${initialInd}${node.op}${
        node.without
          ? ` without(${node.grouping.join(", ")}) `
          : node.grouping.length > 0
            ? ` by(${node.grouping.join(", ")}) `
            : ""
      }(${childListSeparator}${
        aggregatorsWithParam.includes(node.op) && node.param !== null
          ? `${serializeNode(node.param, childIndent, pretty)},${childSeparator}`
          : ""
      }${serializeNode(node.expr, childIndent, pretty)}${childListSeparator}${ind})`;

    case nodeType.subquery:
      return `${initialInd}${serializeNode(node.expr, indent, pretty)}[${formatPrometheusDuration(node.range)}:${
        node.step !== 0 ? formatPrometheusDuration(node.step) : ""
      }]${serializeAtAndOffset(node.timestamp, node.startOrEnd, node.offset)}`;

    case nodeType.parenExpr:
      return `${initialInd}(${childListSeparator}${serializeNode(
        node.expr,
        childIndent,
        pretty
      )}${childListSeparator}${ind})`;

    case nodeType.call: {
      const sep = node.args.length > 0 ? childListSeparator : "";

      return `${initialInd}${node.func.name}(${sep}${node.args
        .map((arg) => serializeNode(arg, childIndent, pretty))
        .join("," + childSeparator)}${sep}${node.args.length > 0 ? ind : ""})`;
    }

    case nodeType.matrixSelector:
      return `${initialInd}${serializeSelector(node)}`;

    case nodeType.vectorSelector:
      return `${initialInd}${serializeSelector(node)}`;

    case nodeType.numberLiteral:
      return `${initialInd}${node.val}`;

    case nodeType.stringLiteral:
      return `${initialInd}"${escapeString(node.val)}"`;

    case nodeType.unaryExpr:
      return `${initialInd}${node.op}${serializeNode(node.expr, indent, pretty, false)}`;

    case nodeType.binaryExpr: {
      let matching = "";
      let grouping = "";
      const vm = node.matching;
      if (vm !== null && (vm.labels.length > 0 || vm.on)) {
        if (vm.on) {
          matching = ` on(${vm.labels.join(", ")})`;
        } else {
          matching = ` ignoring(${vm.labels.join(", ")})`;
        }

        if (
          vm.card === vectorMatchCardinality.manyToOne ||
          vm.card === vectorMatchCardinality.oneToMany
        ) {
          grouping = ` group_${vm.card === vectorMatchCardinality.manyToOne ? "left" : "right"}(${vm.include.join(",")})`;
        }
      }

      return `${serializeNode(maybeParenthesizeBinopChild(node.op, node.lhs), childIndent, pretty)}${childSeparator}${ind}${
        node.op
      }${node.bool ? " bool" : ""}${matching}${grouping}${childSeparator}${serializeNode(
        maybeParenthesizeBinopChild(node.op, node.rhs),
        childIndent,
        pretty
      )}`;
    }

    case nodeType.placeholder:
      // TODO: Should we just throw an error when trying to serialize an AST containing a placeholder node?
      // (that would currently break editing-as-text of ASTs that contain placeholders)
      return `${initialInd}…${
        node.children.length > 0
          ? `(${childListSeparator}${node.children
              .map((child) => serializeNode(child, childIndent, pretty))
              .join("," + childSeparator)}${childListSeparator}${ind})`
          : ""
      }`;

    default:
      throw new Error("unsupported node type");
  }
};

export default serializeNode;