/**
 * Tests the 'reconfigForPSASet()' shell function and makes sure that reconfig will succeed while
 * preserving majority reads.
 *
 * @tags: [requires_replication]
 */

(function() {
'use strict';

load("jstests/replsets/rslib.js");

// Start up a PSA set with the secondary having 'votes: 0' and 'priority: 0'.
const rst = new ReplSetTest({
    name: jsTestName(),
    nodes: [{}, {rsConfig: {votes: 0, priority: 0}}, {rsConfig: {arbiterOnly: true}}],
});
rst.startSet();
rst.initiateWithHighElectionTimeout();

const primary = rst.getPrimary();
assert.eq(primary, rst.nodes[0], "the primary should be the node at index 0");

// Store the old config so that we can reset to it after every successful reconfig.
const originalConfig = rst.getReplSetConfigFromNode();

// Verify that directly calling the standard 'rs.reconfig()' function to give the secondary 'votes:
// 1' and 'priority: 1' will fail.
let config = rst.getReplSetConfigFromNode();
config.members[1].votes = 1;
config.members[1].priority = 1;

jsTestLog("Testing standard rs.reconfig() function");
const reconfigScript = `assert.commandFailedWithCode(rs.reconfig(${
    tojson(config)}), ErrorCodes.NewReplicaSetConfigurationIncompatible)`;
const result = runMongoProgram('mongo', '--port', primary.port, '--eval', reconfigScript);
assert.eq(0, result, `reconfig did not fail with expected error code`);

const runReconfigForPSASet = (memberIndex, config, shouldSucceed, endPriority = 1) => {
    jsTestLog(`Testing with memberIndex ${memberIndex} and config ${tojson(config)}`);

    const reconfigScript =
        `assert.commandWorked(rs.reconfigForPSASet(${memberIndex}, ${tojson(config)}))`;
    const result = runMongoProgram('mongo', '--port', primary.port, '--eval', reconfigScript);
    if (shouldSucceed) {
        assert.eq(0, result, 'expected reconfigToPSASet to succeed, but it failed');

        // Wait for all 'newlyAdded' fields to be removed and for the new config to be committed.
        rst.waitForAllNewlyAddedRemovals();
        assert.soonNoExcept(() => isConfigCommitted(primary));

        const replSetGetConfig =
            assert.commandWorked(primary.adminCommand({replSetGetConfig: 1})).config;
        assert.eq(1, replSetGetConfig.members[1].votes);
        assert.eq(endPriority, replSetGetConfig.members[1].priority);

        // Reset the config back to the original config.
        originalConfig.members[memberIndex].votes = 0;
        originalConfig.members[memberIndex].priority = 0;
        const reconfigToOriginalConfig =
            `assert.commandWorked(rs.reconfig(${tojson(originalConfig)}))`;
        assert.eq(
            0,
            runMongoProgram('mongo', '--port', primary.port, '--eval', reconfigToOriginalConfig));
        assert.soonNoExcept(() => isConfigCommitted(primary));
    } else {
        assert.neq(0, result, 'expected reconfigToPSASet to fail, but it succeeded');
    }
};

// Succeed with a reconfig to a standard PSA set, where the secondary has 'votes: 1' and 'priority:
// 1'.
jsTestLog("Testing reconfigForPSASet() succeeded: standard PSA set");
runReconfigForPSASet(1, config, true /* shouldSucceed */);

// Fail when 'memberIndex' does not refer to a node in the new config.
jsTestLog("Testing reconfigForPSASet() failed: memberIndex out of bounds");
runReconfigForPSASet(3, config, false /* shouldSucceed */);

// Fail when the node in the new config at 'memberIndex' is not a voter.
jsTestLog("Testing reconfigForPSASet() failed: node at memberIndex is not a voter");
config.members[1].votes = 0;
config.members[1].priority = 0;
runReconfigForPSASet(1, config, false /* shouldSucceed */);

// Test that reconfigToPSASet() will succeed when we are adding a new node at a specific
// 'memberIndex'.
jsTestLog("Testing reconfigForPSASet() succeeded: adding new node");

// First remove the node at index 1 to simulate a two-node replica set.
config = rst.getReplSetConfigFromNode();
const filteredMembers = config.members.filter(member => member._id !== 1);
config.members = filteredMembers;
config.version += 1;
assert.commandWorked(primary.adminCommand({replSetReconfig: config}));

// Attempt to add a node and assert that the reconfigToPSASet() call is successful.
config.members = originalConfig.members;
config.members[1].votes = 1;
config.members[1].priority = 1;
config.version += 1;
runReconfigForPSASet(1, config, true /* shouldSucceed */);

// Test that reconfigToPSASet() will succeed even if the priority of the node is 0 in the final
// config.
jsTestLog("Testing reconfigForPSASet() succeeded: priority of node is 0 in final config");
config = rst.getReplSetConfigFromNode();
config.members[1].votes = 1;
config.members[1].priority = 0;
runReconfigForPSASet(1, config, true /* shouldSucceed */, 0 /* endPriority */);

// Test that reconfigToPSASet() will fail if the node at 'memberIndex' exists in the old config but
// was a voter. It should fail because this is not the use case of the helper function.
jsTestLog("Testing reconfigForPSASet() failed: node at memberIndex was a voter in old config");

// First turn the secondary into a voting node but with priority 0.
config = rst.getReplSetConfigFromNode();
config.members[1].votes = 1;
config.members[1].priority = 0;
config.version += 1;
assert.commandWorked(primary.adminCommand({replSetReconfig: config}));

// Now attempt a reconfig to give the secondary priority 1 via the reconfigForPSASet() function.
// This should fail because this function should not be used if the secondary is a voter in the old
// config.
config.members[1].priority = 1;
config.version += 1;
runReconfigForPSASet(1, config, false /* shouldSucceed */);

rst.stopSet();
})();