// Copyright 2020 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

package main

import (
	"bufio"
	"bytes"
	"context"
	"flag"
	"fmt"
	"math/rand"
	"net/http"
	"os"
	"path/filepath"
	"runtime"
	"sort"
	"strings"
	"sync"
	"sync/atomic"

	"go.skia.org/infra/go/exec"
	"go.skia.org/infra/go/util"
	"go.skia.org/infra/task_driver/go/td"
)

func main() {
	var (
		projectId = flag.String("project_id", "", "ID of the Google Cloud project.")
		taskId    = flag.String("task_id", "", "ID of this task.")
		bot       = flag.String("bot", "", "Name of the task.")
		output    = flag.String("o", "", "Dump JSON step data to the given file, or stdout if -.")
		local     = flag.Bool("local", true, "Running locally (else on the bots)?")

		resources     = flag.String("resources", "resources", "Passed to fm -i.")
		imgs          = flag.String("imgs", "", "Shorthand `directory` contents as 'imgs'.")
		skps          = flag.String("skps", "", "Shorthand `directory` contents as 'skps'.")
		svgs          = flag.String("svgs", "", "Shorthand `directory` contents as 'svgs'.")
		script        = flag.String("script", "", "File (or - for stdin) with one job per line.")
		gold          = flag.Bool("gold", false, "Fetch known hashes, upload to Gold, etc.?")
		goldHashesURL = flag.String("gold_hashes_url", "", "URL from which to download pre-existing hashes")
	)
	flag.Parse()

	ctx := context.Background()
	startStep := func(ctx context.Context, _ *td.StepProperties) context.Context { return ctx }
	endStep := func(_ context.Context) {}
	failStep := func(_ context.Context, err error) error {
		fmt.Fprintln(os.Stderr, err)
		return err
	}
	fatal := func(ctx context.Context, err error) {
		failStep(ctx, err)
		os.Exit(1)
	}
	httpClient := func(_ context.Context) *http.Client { return http.DefaultClient }

	if !*local {
		ctx = td.StartRun(projectId, taskId, bot, output, local)
		defer td.EndRun(ctx)
		startStep = td.StartStep
		endStep = td.EndStep
		failStep = td.FailStep
		fatal = td.Fatal
		httpClient = func(ctx context.Context) *http.Client { return td.HttpClient(ctx, nil) }
	}

	if flag.NArg() < 1 {
		fatal(ctx, fmt.Errorf("Please pass an fm binary."))
	}
	fm := flag.Arg(0)

	// Run `fm <flag>` to find the names of all linked GMs or tests.
	query := func(flag string) []string {
		stdout := &bytes.Buffer{}
		cmd := &exec.Command{Name: fm, Stdout: stdout}
		cmd.Args = append(cmd.Args, "-i", *resources)
		cmd.Args = append(cmd.Args, flag)
		if err := exec.Run(ctx, cmd); err != nil {
			fatal(ctx, err)
		}

		lines := []string{}
		scanner := bufio.NewScanner(stdout)
		for scanner.Scan() {
			lines = append(lines, scanner.Text())
		}
		if err := scanner.Err(); err != nil {
			fatal(ctx, err)
		}
		return lines
	}

	// Lowercase with leading '.' stripped.
	normalizedExt := func(s string) string {
		return strings.ToLower(filepath.Ext(s)[1:])
	}

	// Walk directory for files with given set of extensions.
	walk := func(dir string, exts map[string]bool) (files []string) {
		if dir != "" {
			err := filepath.Walk(dir, func(path string, info os.FileInfo, err error) error {
				if err != nil {
					return err
				}
				if !info.IsDir() && exts[normalizedExt(info.Name())] {
					files = append(files, path)
				}
				return nil
			})

			if err != nil {
				fatal(ctx, err)
			}
		}
		return
	}

	rawExts := map[string]bool{
		"arw": true,
		"cr2": true,
		"dng": true,
		"nef": true,
		"nrw": true,
		"orf": true,
		"pef": true,
		"raf": true,
		"rw2": true,
		"srw": true,
	}
	imgExts := map[string]bool{
		"astc": true,
		"bmp":  true,
		"gif":  true,
		"ico":  true,
		"jpeg": true,
		"jpg":  true,
		"ktx":  true,
		"png":  true,
		"wbmp": true,
		"webp": true,
	}
	for k, v := range rawExts {
		imgExts[k] = v
	}

	// We can use "gm" or "gms" as shorthand to refer to all GMs, and similar for the rest.
	shorthands := map[string][]string{
		"gm":   query("--listGMs"),
		"test": query("--listTests"),
		"img":  walk(*imgs, imgExts),
		"skp":  walk(*skps, map[string]bool{"skp": true}),
		"svg":  walk(*svgs, map[string]bool{"svg": true}),
	}
	for k, v := range shorthands {
		shorthands[k+"s"] = v
	}

	// Query Gold for all known hashes when running as a bot.
	known := map[string]bool{
		"0832f708a97acc6da385446384647a8f": true, // MD5 of passing unit test.
	}
	if *gold {
		func() {
			resp, err := httpClient(ctx).Get(*goldHashesURL)
			if err != nil {
				fatal(ctx, err)
			}
			defer resp.Body.Close()

			scanner := bufio.NewScanner(resp.Body)
			for scanner.Scan() {
				known[scanner.Text()] = true
			}
			if err := scanner.Err(); err != nil {
				fatal(ctx, err)
			}

			fmt.Fprintf(os.Stdout, "Gold knew %v unique hashes.\n", len(known))
		}()
	}

	// We'll pass `flag: value` as `--flag value` to FM.
	// Such a short type name makes it easy to write out literals.
	type F = map[string]string

	flatten := func(flags F) (flat []string) {
		// It's not strictly important that we sort, but it makes reading bot logs easier.
		keys := []string{}
		for k := range flags {
			keys = append(keys, k)
		}
		sort.Strings(keys)

		for _, k := range keys {
			v := flags[k]

			if v == "true" {
				flat = append(flat, "--"+k)
			} else if v == "false" {
				flat = append(flat, "--no"+k)
			} else if len(k) == 1 {
				flat = append(flat, "-"+k, v)
			} else {
				flat = append(flat, "--"+k, v)
			}
		}
		return
	}

	var worker func(context.Context, []string, F) int
	worker = func(ctx context.Context, sources []string, flags F) (failures int) {
		stdout := &bytes.Buffer{}
		stderr := &bytes.Buffer{}
		cmd := &exec.Command{Name: fm, Stdout: stdout, Stderr: stderr}
		cmd.Args = append(cmd.Args, "-i", *resources)
		cmd.Args = append(cmd.Args, flatten(flags)...)
		cmd.Args = append(cmd.Args, "-s")
		cmd.Args = append(cmd.Args, sources...)

		// Run our FM command.
		err := exec.Run(ctx, cmd)

		// We'll rerun any source individually that didn't produce a known hash, i.e.
		// sources that crash, produce unknown hashes, or that an crash prevented from running.
		unknownHash := ""
		{
			// Start assuming we'll need to rerun everything.
			reruns := map[string]bool{}
			for _, name := range sources {
				reruns[name] = true
			}

			// Scan stdout for lines like "<name> skipped" or "<name> <hash> ??ms"
			// and exempt those sources from reruns if they were skipped or their hash is known.
			scanner := bufio.NewScanner(stdout)
			for scanner.Scan() {
				if parts := strings.Fields(scanner.Text()); len(parts) >= 2 {
					name, outcome := parts[0], parts[1]
					if *gold && outcome != "skipped" && !known[outcome] {
						unknownHash = outcome
					} else {
						delete(reruns, name)
					}
				}
			}
			if err := scanner.Err(); err != nil {
				fatal(ctx, err)
			}

			// Only rerun sources from a batch (or we'd rerun failures over and over and over).
			if len(sources) > 1 {
				for name := range reruns {
					failures += worker(ctx, []string{name}, flags)
				}
				return
			}
		}

		// If an individual run failed, nothing more to do but fail.
		if err != nil {
			failures += 1

			lines := []string{}
			scanner := bufio.NewScanner(stderr)
			for scanner.Scan() {
				lines = append(lines, scanner.Text())
			}
			if err := scanner.Err(); err != nil {
				fatal(ctx, err)
			}

			failStep(ctx, fmt.Errorf("%v #failed:\n\t%v\n",
				exec.DebugString(cmd),
				strings.Join(lines, "\n\t")))

			return
		}

		// If an individual run succeeded but produced an unknown hash, TODO upload .png to Gold.
		// For now just print out the command and the hash it produced.
		if unknownHash != "" {
			fmt.Fprintf(os.Stdout, "%v #%v\n",
				exec.DebugString(cmd),
				unknownHash)
		}
		return
	}

	type Work struct {
		Ctx      context.Context
		WG       *sync.WaitGroup
		Failures *int32
		Sources  []string // Passed to FM -s: names of gms/tests, paths to images, .skps, etc.
		Flags    F        // Other flags to pass to FM: --ct 565, --msaa 16, etc.
	}
	queue := make(chan Work, 1<<20) // Arbitrarily huge buffer to avoid ever blocking.

	for i := 0; i < runtime.NumCPU(); i++ {
		go func() {
			for w := range queue {
				func() {
					defer w.WG.Done()
					// For organizational purposes, create a step representing this batch,
					// with the batch call to FM and any individual reruns all nested inside.
					ctx := startStep(w.Ctx, td.Props(strings.Join(w.Sources, " ")))
					defer endStep(ctx)
					if failures := worker(ctx, w.Sources, w.Flags); failures > 0 {
						atomic.AddInt32(w.Failures, int32(failures))
						if !*local { // Uninteresting to see on local runs.
							failStep(ctx, fmt.Errorf("%v reruns failed\n", failures))
						}
					}
				}()
			}
		}()
	}

	// Get some work going, first breaking it into batches to increase our parallelism.
	pendingKickoffs := &sync.WaitGroup{}
	var totalFailures int32 = 0

	kickoff := func(sources []string, flags F) {
		if len(sources) == 0 {
			return // A blank or commented job line from -script or the command line.
		}
		pendingKickoffs.Add(1)

		// Shuffle the sources randomly as a cheap way to approximate evenly expensive batches.
		// (Intentionally not rand.Seed()'d to stay deterministically reproducible.)
		sources = append([]string{}, sources...) // We'll be needing our own copy...
		rand.Shuffle(len(sources), func(i, j int) {
			sources[i], sources[j] = sources[j], sources[i]
		})

		// For organizational purposes, create a step representing this call to kickoff(),
		// with each batch of sources nested inside.
		ctx := startStep(ctx,
			td.Props(fmt.Sprintf("%s, %s…", strings.Join(flatten(flags), " "), sources[0])))
		pendingBatches := &sync.WaitGroup{}
		failures := new(int32)

		// Arbitrary, nice to scale ~= cores.
		approxNumBatches := runtime.NumCPU()

		// Round up batch size to avoid empty batches, making approxNumBatches approximate.
		batchSize := (len(sources) + approxNumBatches - 1) / approxNumBatches

		util.ChunkIter(len(sources), batchSize, func(start, end int) error {
			pendingBatches.Add(1)
			queue <- Work{ctx, pendingBatches, failures, sources[start:end], flags}
			return nil
		})

		// When the batches for this kickoff() are all done, this kickoff() is done.
		go func() {
			pendingBatches.Wait()
			if *failures > 0 {
				atomic.AddInt32(&totalFailures, *failures)
				if !*local { // Uninteresting to see on local runs.
					failStep(ctx, fmt.Errorf("%v total reruns failed\n", *failures))
				}
			}
			endStep(ctx)
			pendingKickoffs.Done()
		}()
	}

	// Parse a job like "gms b=cpu ct=8888" into sources and flags for kickoff().
	parse := func(job []string) (sources []string, flags F) {
		flags = make(F)
		for _, token := range job {
			// Everything after # is a comment.
			if strings.HasPrefix(token, "#") {
				break
			}

			// Expand "gm" or "gms"  to all known GMs, or same for tests, images, skps, svgs.
			if vals, ok := shorthands[token]; ok {
				sources = append(sources, vals...)
				continue
			}

			// Is this a flag to pass through to FM?
			if parts := strings.Split(token, "="); len(parts) == 2 {
				flags[parts[0]] = parts[1]
				continue
			}

			// Anything else must be the name of a source for FM to run.
			sources = append(sources, token)
		}
		return
	}

	// Parse one job from the command line, handy for ad hoc local runs.
	kickoff(parse(flag.Args()[1:]))

	// Any number of jobs can come from -script.
	if *script != "" {
		file := os.Stdin
		if *script != "-" {
			file, err := os.Open(*script)
			if err != nil {
				fatal(ctx, err)
			}
			defer file.Close()
		}
		scanner := bufio.NewScanner(file)
		for scanner.Scan() {
			kickoff(parse(strings.Fields(scanner.Text())))
		}
		if err := scanner.Err(); err != nil {
			fatal(ctx, err)
		}
	}

	// If we're a bot (or acting as if we are one), kick off its work.
	if *bot != "" {
		parts := strings.Split(*bot, "-")
		OS, model, CPU_or_GPU := parts[1], parts[3], parts[4]

		// Bots use portable fonts except where we explicitly opt-in to native fonts.
		defaultFlags := F{"nativeFonts": "false"}

		run := func(sources []string, extraFlags F) {
			// Default then extra to allow overriding the defaults.
			flags := F{}
			for k, v := range defaultFlags {
				flags[k] = v
			}
			for k, v := range extraFlags {
				flags[k] = v
			}
			kickoff(sources, flags)
		}

		gms := shorthands["gms"]
		imgs := shorthands["imgs"]
		svgs := shorthands["svgs"]
		skps := shorthands["skps"]
		tests := shorthands["tests"]

		filter := func(in []string, keep func(string) bool) (out []string) {
			for _, s := range in {
				if keep(s) {
					out = append(out, s)
				}
			}
			return
		}

		if strings.Contains(OS, "Win") {
			// We can't decode these formats on Windows.
			imgs = filter(imgs, func(s string) bool { return !rawExts[normalizedExt(s)] })
		}

		if strings.Contains(*bot, "TSAN") {
			// Run each test a few times in parallel to uncover races.
			defaultFlags["race"] = "4"
		}

		if CPU_or_GPU == "CPU" {
			defaultFlags["b"] = "cpu"

			// FM's default ct/gamut/tf flags are equivalent to --config srgb in DM.
			run(gms, F{})
			run(gms, F{"nativeFonts": "true"})
			run(imgs, F{})
			run(svgs, F{})
			run(skps, F{"clipW": "1000", "clipH": "1000"})
			run(tests, F{"race": "0"}) // Several unit tests are not reentrant.

			if model == "GCE" {
				run(gms, F{"ct": "g8", "legacy": "true"})                     // --config g8
				run(gms, F{"ct": "565", "legacy": "true"})                    // --config 565
				run(gms, F{"ct": "8888", "legacy": "true"})                   // --config 8888
				run(gms, F{"ct": "f16"})                                      // --config esrgb
				run(gms, F{"ct": "f16", "tf": "linear"})                      // --config f16
				run(gms, F{"ct": "8888", "gamut": "p3"})                      // --config p3
				run(gms, F{"ct": "8888", "gamut": "narrow", "tf": "2.2"})     // --config narrow
				run(gms, F{"ct": "f16", "gamut": "rec2020", "tf": "rec2020"}) // --config erec2020

				run(gms, F{"skvm": "true"})
				run(gms, F{"skvm": "true", "ct": "f16"})

				run(imgs, F{
					"decodeToDst": "true",
					"ct":          "f16",
					"gamut":       "rec2020",
					"tf":          "rec2020"})
			}

			// TODO: pic-8888 equivalent?
			// TODO: serialize-8888 equivalent?
		}
	}

	pendingKickoffs.Wait()
	if totalFailures > 0 {
		fatal(ctx, fmt.Errorf("%v runs of %v failed after retries.\n", totalFailures, fm))
	}
}