package mdb

import (
	"math/rand"
	"os"
	"sync"
	"testing"
	"time"

	"git.crumpington.com/private/mdb/testconn"
)

func TestShipping(t *testing.T) {
	run := func(name string, inner func(t *testing.T, db1 *DB, db2 *DB, network *testconn.Network)) {
		t.Run(name, func(t *testing.T) {
			root1, err := os.MkdirTemp("", "")
			must(err)
			defer os.RemoveAll(root1)
			root2, err := os.MkdirTemp("", "")
			must(err)
			defer os.RemoveAll(root2)

			db1 := OpenDB(root1, true)
			defer db1.Close()
			db2 := OpenDB(root2, false)
			defer db2.Close()

			inner(t, db1, db2, testconn.NewNetwork())
		})
	}

	run("simple", func(t *testing.T, db, db2 *DB, network *testconn.Network) {
		wg := sync.WaitGroup{}
		wg.Add(2)

		// Send in background.
		go func() {
			defer wg.Done()
			conn := network.Accept()
			db.SyncSend(conn)
		}()

		// Recv in background.
		go func() {
			defer wg.Done()
			conn := network.Dial()
			db2.SyncRecv(conn)
		}()

		for i := 0; i < 100; i++ {
			db.RandAction()
		}

		db.WaitForSync(db2)
		network.CloseClient()
		wg.Wait()

		if err := db.Equals(db2); err != nil {
			t.Fatal(err)
		}
	})

	run("simple multiple writers", func(t *testing.T, db, db2 *DB, network *testconn.Network) {
		wg := sync.WaitGroup{}

		// Send in background.
		wg.Add(1)
		go func() {
			defer wg.Done()
			conn := network.Accept()
			db.SyncSend(conn)
		}()

		// Recv in background.
		wg.Add(1)
		go func() {
			defer wg.Done()
			conn := network.Dial()
			db2.SyncRecv(conn)
		}()

		updateWG := sync.WaitGroup{}
		updateWG.Add(64)
		for i := 0; i < 64; i++ {
			go func() {
				defer updateWG.Done()
				for j := 0; j < 1024; j++ {
					db.RandAction()
				}
			}()
		}

		updateWG.Wait()

		db.WaitForSync(db2)
		network.CloseClient()
		wg.Wait()

		if err := db.Equals(db2); err != nil {
			t.Fatal(err)
		}
	})

	run("unstable network", func(t *testing.T, db, db2 *DB, network *testconn.Network) {
		sleepTimeout := time.Millisecond

		updateWG := sync.WaitGroup{}
		updateWG.Add(64)
		for i := 0; i < 64; i++ {
			go func() {
				defer updateWG.Done()
				for j := 0; j < 4096; j++ {
					time.Sleep(sleepTimeout)
					db.RandAction()
				}
			}()
		}

		updating := &atomicBool{}
		updating.Set(true)

		go func() {
			updateWG.Wait()
			updating.Set(false)
		}()

		// Recv in background.
		recving := &atomicBool{}
		recving.Set(true)
		go func() {
			for {
				// Stop when no longer updating and WAL files match.
				if !updating.Get() {
					if db.MaxSeqNum() == db2.MaxSeqNum() {
						recving.Set(false)
						return
					}
				}

				if conn := network.Dial(); conn != nil {
					db2.SyncRecv(conn)
				}
			}
		}()

		// Send in background.
		sending := &atomicBool{}
		sending.Set(true)
		go func() {
			for {
				// Stop when no longer updating and WAL files match.
				if !updating.Get() {
					if db.MaxSeqNum() == db2.MaxSeqNum() {
						sending.Set(false)
						return
					}
				}

				if conn := network.Accept(); conn != nil {
					db.SyncSend(conn)
				}
			}
		}()

		// Interrupt network periodically as long as sending or receiving.
		for sending.Get() || recving.Get() {
			time.Sleep(time.Duration(rand.Intn(10 * int(sleepTimeout))))
			if rand.Float64() < 0.5 {
				network.CloseClient()
			} else {
				network.CloseServer()
			}
		}

		if err := db.Equals(db2); err != nil {
			t.Fatal(err)
		}
	})
}