Implement bare-bones sc2 merge and score (#1815)

This adds the missing `merge` and `score` commands to the sc2 CLI.
`merge` currently just merges the plugin graphs, and doesn't yet support
identity resolution or weight overrides.

`score` computes the new data output format (cf #1773) and writes it to
disk. It doesn't yet support using custom parameters.

Test plan:
Follow the test plans for the previous commits, then run `sc2 merge`.
It will create a combined graph at `output/graph.json`, which will
contain data for both Discourse and GitHub. Then run `sc2 score` and
the `output/cred.json` file will contain scores for the combined
graph.

src/cli2/merge.js

@@ -0,0 +1,53 @@
+// @flow
+
+import fs from "fs-extra";
+import stringify from "json-stable-stringify";
+import {join as pathJoin} from "path";
+
+import {LoggingTaskReporter} from "../util/taskReporter";
+import type {Command} from "./command";
+import {makePluginDir, loadInstanceConfig} from "./common";
+import {
+  toJSON as weightedGraphToJSON,
+  fromJSON as weightedGraphFromJSON,
+  type WeightedGraph,
+  merge,
+} from "../core/weightedGraph";
+
+function die(std, message) {
+  std.err("fatal: " + message);
+  return 1;
+}
+
+const mergeCommand: Command = async (args, std) => {
+  if (args.length !== 0) {
+    return die(std, "usage: sourcecred merge");
+  }
+  const taskReporter = new LoggingTaskReporter();
+  taskReporter.start("merge");
+  const baseDir = process.cwd();
+  const config = await loadInstanceConfig(baseDir);
+  const graphOutputPrefix = ["output", "graphs"];
+
+  async function loadGraph(pluginName): Promise<WeightedGraph> {
+    const outputDir = makePluginDir(baseDir, graphOutputPrefix, pluginName);
+    const outputPath = pathJoin(outputDir, "graph.json");
+    const graphJSON = JSON.parse(await fs.readFile(outputPath));
+    return weightedGraphFromJSON(graphJSON);
+  }
+
+  const pluginNames = Array.from(config.bundledPlugins.keys());
+  const graphs = await Promise.all(pluginNames.map(loadGraph));
+
+  // TODO: Support identity merging.
+  // TODO: Support weight overrides.
+  const combinedGraph = merge(graphs);
+
+  const outputPath = pathJoin(baseDir, "output", "graph.json");
+  const serializedGraph = stringify(weightedGraphToJSON(combinedGraph));
+  await fs.writeFile(outputPath, serializedGraph);
+  taskReporter.finish("merge");
+  return 0;
+};
+
+export default mergeCommand;

src/cli2/score.js

@@ -0,0 +1,56 @@
+// @flow
+
+import fs from "fs-extra";
+import stringify from "json-stable-stringify";
+import {join as pathJoin} from "path";
+
+import type {Command} from "./command";
+import {loadInstanceConfig} from "./common";
+import {fromJSON as weightedGraphFromJSON} from "../core/weightedGraph";
+import {defaultParams} from "../analysis/timeline/params";
+import {TimelineCred} from "../analysis/timeline/timelineCred";
+import {LoggingTaskReporter} from "../util/taskReporter";
+import {
+  fromTimelineCredAndPlugins,
+  COMPAT_INFO as OUTPUT_COMPAT_INFO,
+} from "../analysis/output";
+import {toCompat} from "../util/compat";
+
+function die(std, message) {
+  std.err("fatal: " + message);
+  return 1;
+}
+
+const scoreCommand: Command = async (args, std) => {
+  if (args.length !== 0) {
+    return die(std, "usage: sourcecred score");
+  }
+  const taskReporter = new LoggingTaskReporter();
+  taskReporter.start("score");
+  const baseDir = process.cwd();
+  const config = await loadInstanceConfig(baseDir);
+
+  const graphFilePath = pathJoin(baseDir, "output", "graph.json");
+  const graphJSON = JSON.parse(await fs.readFile(graphFilePath));
+  const graph = weightedGraphFromJSON(graphJSON);
+
+  const plugins = Array.from(config.bundledPlugins.values());
+  const declarations = plugins.map((x) => x.declaration());
+
+  // TODO: Support loading params from config.
+  const params = defaultParams();
+
+  const tc = await TimelineCred.compute({
+    weightedGraph: graph,
+    params,
+    plugins: declarations,
+  });
+  const output = fromTimelineCredAndPlugins(tc, declarations);
+  const outputJSON = stringify(toCompat(OUTPUT_COMPAT_INFO, output));
+  const outputPath = pathJoin(baseDir, "output", "cred.json");
+  await fs.writeFile(outputPath, outputJSON);
+  taskReporter.finish("score");
+  return 0;
+};
+
+export default scoreCommand;

src/cli2/sourcecred.js

@@ -4,6 +4,8 @@ import type {Command} from "./command";
 
 import load from "./load";
 import graph from "./graph";
+import merge from "./merge";
+import score from "./score";
 
 const sourcecred: Command = async (args, std) => {
   if (args.length === 0) {
@@ -15,6 +17,10 @@ const sourcecred: Command = async (args, std) => {
       return load(args.slice(1), std);
     case "graph":
       return graph(args.slice(1), std);
+    case "merge":
+      return merge(args.slice(1), std);
+    case "score":
+      return score(args.slice(1), std);
     default:
       std.err("fatal: unknown command: " + JSON.stringify(args[0]));
       return 1;