// Copyright 2023 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

package build

import (
	"bytes"
	"context"
	"encoding/base64"
	"fmt"
	"iter"
	"path/filepath"
	"strings"
	"sync"
	"time"

	rpb "github.com/bazelbuild/remote-apis/build/bazel/remote/execution/v2"
	log "github.com/golang/glog"

	"go.chromium.org/build/siso/execute"
	"go.chromium.org/build/siso/execute/reproxyexec"
	"go.chromium.org/build/siso/o11y/clog"
	"go.chromium.org/build/siso/o11y/trace"
	"go.chromium.org/build/siso/reapi/digest"
)

// StepDef is a build step definition.
// Unless specified, path is workspace relative.
type StepDef interface {
	// String returns id of the step.
	String() string

	// Next returns next step's def.
	Next() StepDef

	// Ensure siso rule is applied
	EnsureRule(context.Context)

	// RuleName returns rule name of the step. empty for no rule.
	RuleName() string

	// ActionName returns action name of the step.
	ActionName() string

	// Args returns command line arguments of the step.
	Args(context.Context) []string

	// IsPhony returns true if the step is phony.
	IsPhony() bool

	// CmdHash returns command hash of the step.
	CmdHash() []byte

	// Binding returns binding value.
	Binding(string) string

	// Depfile returns workspace relative depfile path, or empty if not set.
	Depfile(context.Context) string

	// Rspfile returns workspace relative rspfile path, or empty if not set.
	Rspfile(context.Context) string

	// Inputs returns inputs of the step.
	Inputs(context.Context) []string

	// TriggerInputs returns inputs of the step that would trigger
	// the step's action.  no order-only.
	// For  deps in deps log, use DepInputs.
	TriggerInputs(context.Context) []string

	// DepInputs returns iterator for inputs via depfile of the step.
	// if depfile is not set, returns emptyIter, nil
	// if depfile or deplog is not found, returns wrapped ErrMissingDeps.
	DepInputs(context.Context) (iter.Seq[string], error)

	// DepsBaseInputs returns inputs of the step, which will be combined
	// with scandeps results.
	DepsBaseInputs(context.Context, []string) []string

	// ToolInputs returns tool inputs of the step.
	// ToolInputs is added to deps inputs.
	ToolInputs(context.Context) []string

	// ExpandedCaseSensitives returns expanded filenames if platform is case-sensitive.
	ExpandedCaseSensitives(context.Context, []string) []string

	// ExpandedInputs returns expanded inputs of the step.
	ExpandedInputs(context.Context) []string

	// RemoteInputs maps file used in remote to file exists on local.
	// path in remote action -> local path
	RemoteInputs() map[string]string

	// REProxyConfig returns configuration options for using reproxy.
	REProxyConfig() *execute.REProxyConfig

	// CheckInputDeps checks dep can be found in its direct/indirect inputs.
	// Returns true if it is unknown bad deps, false otherwise.
	CheckInputDeps(context.Context, []string) (bool, error)

	// Handle runs a handler for the cmd.
	Handle(context.Context, *execute.Cmd) error

	// Outputs returns outputs of the step.
	Outputs(context.Context) []string

	// LocalOutputs returns outputs of the step that should be written to the local disk.
	LocalOutputs(context.Context) []string

	// AuxiliaryLogOutputFiles returns output files that siso explicitly logs digest of
	// but doesn't download to disk.
	AuxiliaryLogOutputFiles(context.Context) []string

	// AuxiliaryLogOutputDirs returns output directories that siso explicitly logs digest of
	// but doesn't download to disk.
	AuxiliaryLogOutputDirs(context.Context) []string

	// Pure indicates the step is pure or not.
	Pure() bool

	// Platform returns platform properties for remote execution.
	Platform() map[string]string

	// Sandbox returns properties for action sandboxing.
	Sandbox() map[string]string

	// RecordDeps records deps.
	RecordDeps(context.Context, string, time.Time, digest.Digest, []string) (bool, error)

	// RuleFix returns required fix for the rule of the step.
	RuleFix(ctx context.Context, inadds, outadds []string) []byte
}

// Edge contains StepDef and the dependency targets of the edge.
type Edge struct {
	StepDef     StepDef
	Inputs      []Target
	OrderOnly   []Target
	Outputs     []Target
	Validations []Target
}

// Step is a build step.
type Step struct {
	idnum       int
	def         StepDef
	nwaits      int
	weight      int
	outputs     []Target
	outputPaths []string // target name in ninja, i.e. output path relative to wd.

	cmd *execute.Cmd

	readyTime     time.Time
	prevStepID    string
	queueTime     time.Time
	queueSize     int
	queueDuration time.Duration

	// startTime is the time that the step starts running in a dedicated goroutine.
	// There might be other semaphore throttling for local exec, scandeps, remote exec.
	startTime time.Time

	// endTime is the time that the step ends.
	endTime time.Time

	metrics StepMetric

	// Whether we have reported the start of this step via BuildActionStarted()
	startReported *sync.Once

	// Whether we have reported the finish of this step via BuildActionFinished/Canceled()
	finishReported *sync.Once

	state *stepState
}

// Clone creates a shallow clone of the step with a cloned Cmd
// and fresh mutable state, suitable for the local racer in racing mode.
func (s *Step) Clone() *Step {
	return &Step{
		idnum:          s.idnum,
		def:            s.def,
		weight:         s.weight,
		outputs:        s.outputs,
		outputPaths:    s.outputPaths,
		cmd:            s.cmd.Clone(),
		readyTime:      s.readyTime,
		startTime:      s.startTime,
		state:          &stepState{},
		startReported:  s.startReported,
		finishReported: s.finishReported,
	}
}

// IDNum is a step identification number.
func (s *Step) IDNum() int { return s.idnum }

// Desc returns step's description.
func (s *Step) Desc() string {
	return s.cmd.Desc
}

// Command returns step's command line.
func (s *Step) Command() string {
	return s.def.Binding("command")
}

// Outputs returns step's outputs (target name in ninja, i.e. output path relative to wd.)
func (s *Step) Outputs() []string {
	return s.outputPaths
}

// IsConsole reports whether it uses console pool.
func (s *Step) IsConsole() bool {
	return s.cmd.Console
}

// ExitCode returns exit code of the step.
func (s *Step) ExitCode() int32 {
	return s.cmd.ExitCode()
}

// Stdout returns step's stdout.
func (s *Step) Stdout() []byte {
	return s.cmd.Stdout()
}

// Stderr returns step's stderr.
func (s *Step) Stderr() []byte {
	return s.cmd.Stderr()
}

// OutputResult returns output result of the step.
func (s *Step) OutputResult() string {
	return s.cmd.OutputResult()
}

type stepState struct {
	mu               sync.Mutex
	phase            stepPhase
	weightedDuration time.Duration

	// start time to wait the step to serv.
	// i.e. local semaphore, remote semaphore.
	waitStart time.Time

	// accumulated wait duration in the step.
	waitDuration time.Duration
}

func (s *stepState) SetPhase(phase stepPhase) {
	s.mu.Lock()
	defer s.mu.Unlock()
	s.phase = phase
	switch phase {
	case stepLocalWait, stepREWrapperWait, stepRemoteWait, stepFallbackWait, stepRetryWait:
		s.waitStart = time.Now()
	default:
		if !s.waitStart.IsZero() {
			s.waitDuration += time.Since(s.waitStart)
		}
		s.waitStart = time.Time{}
	}
}

func (s *stepState) Phase() stepPhase {
	s.mu.Lock()
	defer s.mu.Unlock()
	return s.phase
}

func (s *stepState) WaitDuration() time.Duration {
	s.mu.Lock()
	defer s.mu.Unlock()
	dur := s.waitDuration
	if !s.waitStart.IsZero() {
		dur += time.Since(s.waitStart)
	}
	return dur
}

// NumWaits returns number of waits for the step.
func (s *Step) NumWaits() int {
	return s.nwaits
}

// ReadyToRun checks whether the step is ready to run
// when prev step's out becomes ready.
func (s *Step) ReadyToRun(prev string, out Target) bool {
	if out != 0 {
		s.nwaits--
	}
	ready := s.nwaits == 0
	if ready {
		s.readyTime = time.Now()
		s.prevStepID = prev
	}
	return ready
}

// String returns id of the step.
func (s *Step) String() string {
	return s.def.String()
}

type stepPhase int

const (
	stepPhaseNone stepPhase = iota
	stepStart
	stepHandler
	stepPreproc
	stepInput
	stepLocalWait
	stepLocalRun
	stepREWrapperWait
	stepREWrapperRun
	stepRemoteWait
	stepRemoteRun
	stepFallbackWait
	stepFallbackRun
	stepRetryWait
	stepRetryRun
	stepOutput
	stepCacheWrite
	stepCacheWriteWait
	stepDone
)

func (s stepPhase) String() string {
	switch s {
	case stepPhaseNone:
		return "none"
	case stepStart:
		return "start"
	case stepHandler:
		return "handler"
	case stepPreproc:
		return "prep"
	case stepInput:
		return "input"
	case stepLocalWait:
		return "wait-local"
	case stepLocalRun:
		return "local"
	case stepREWrapperWait:
		return "wait-rewrap"
	case stepREWrapperRun:
		return "rewrap"
	case stepRemoteWait:
		return "wait-remote"
	case stepRemoteRun:
		return "remote"
	case stepFallbackWait:
		return "wait-fallback"
	case stepFallbackRun:
		return "fallback"
	case stepRetryWait:
		return "wait-retry"
	case stepRetryRun:
		return "retry"
	case stepOutput:
		return "output"
	case stepCacheWrite:
		return "cache-write"
	case stepCacheWriteWait:
		return "wait-cache-write"
	case stepDone:
		return "done"
	default:
		return "unknown"
	}
}

func (s stepPhase) wait() stepPhase {
	switch s {
	case stepLocalRun:
		return stepLocalWait
	case stepREWrapperRun:
		return stepREWrapperWait
	case stepRemoteRun:
		return stepRemoteWait
	case stepFallbackRun:
		return stepFallbackWait
	case stepRetryRun:
		return stepRetryWait
	case stepCacheWrite:
		return stepCacheWriteWait
	default:
		return s
	}
}

// setPhase sets a phase of the step.
func (s *Step) setPhase(phase stepPhase) {
	s.state.SetPhase(phase)
}

// phase returns the phase of the step.
func (s *Step) phase() stepPhase {
	return s.state.Phase()
}

func (s *Step) servDuration() time.Duration {
	return time.Since(s.startTime) - s.state.WaitDuration()
}

// Done checks the step is done.
func (s *Step) Done() bool {
	return s.state.Phase() == stepDone
}

func (s *Step) addWeightedDuration(d time.Duration) {
	s.state.mu.Lock()
	defer s.state.mu.Unlock()
	if s.state.phase == stepDone {
		return
	}
	s.state.weightedDuration += d
}

func (s *Step) getWeightedDuration() time.Duration {
	s.state.mu.Lock()
	defer s.state.mu.Unlock()
	return s.state.weightedDuration
}

func stepSpanName(stepDef StepDef) string {
	if !strings.HasPrefix(stepDef.ActionName(), "__") {
		return stepDef.ActionName()
	}
	cmd := stepDef.Binding("command")
	i := strings.Index(cmd, " ")
	if i > 0 {
		// use python script as step name, not python binary itself.
		arg0 := cmd[:i]
		if strings.HasSuffix(strings.TrimSuffix(arg0, ".exe"), "python3") {
			cmd = cmd[i+1:]
		}
	}
	i = strings.Index(cmd, " ")
	if i > 0 {
		cmd = cmd[:i]
	}
	return cmd
}

func stepBacktraces(ctx context.Context, step *Step) []string {
	var locs []string
	var prev string
	for s := step.def; s != nil; s = s.Next() {
		var loc string
		if gnTarget := s.Binding("gn_target"); gnTarget != "" {
			loc = gnTarget
		} else {
			outs := s.Outputs(ctx)
			loc = stepSpanName(s)
			if len(outs) > 0 {
				out := outs[0]
				if odir := filepath.Dir(out); odir != "." {
					out = odir
				}
				loc = fmt.Sprintf("%s %s", loc, out)
			}
		}
		if loc != prev {
			locs = append(locs, loc)
			prev = loc
		}
	}
	return locs
}

// useReclient returns true if the step uses Reclient via rewrapper or reproxy.
// A step with reclient doesn't need to collect dependencies and check action result caches on Siso side.
func (s *Step) useReclient() bool {
	return s.def.Binding("use_remote_exec_wrapper") != "" || s.cmd.REProxyConfig != nil
}

func (s *Step) init(ctx context.Context, b *Builder, stepManifest *stepManifest) {
	ctx, span := trace.NewSpan(ctx, "step-init")
	defer span.Close(nil)
	s.startReported = new(sync.Once)
	s.finishReported = new(sync.Once)
	s.def.EnsureRule(ctx)
	s.outputPaths = make([]string, 0, len(stepManifest.outputs))
	for _, out := range stepManifest.outputs {
		s.outputPaths = append(s.outputPaths, b.path.MaybeToRelative(ctx, out))
	}
	s.cmd = newCmd(ctx, b, s.def, stepManifest)
	if log.V(1) {
		clog.Infof(ctx, "cmdhash:%s", base64.StdEncoding.EncodeToString(s.cmd.CmdHash))
	}
}

func newCmd(ctx context.Context, b *Builder, stepDef StepDef, stepManifest *stepManifest) *execute.Cmd {
	// add build.ninja as outputs of gn step.
	// gn uses
	//
	//  build build.ninja.stamp: gn
	//    generator = 1
	//    depfile = build.ninja.d
	//  build build.ninja: phony build.ninja.stamp
	//    generator = 1
	//
	// so, step "gn" has build.ninja.stamp as output, but
	// not build.ninja. but it generates build.ninja
	// so add it as output to make timestamp of build.ninja
	// correctly managed by Siso.
	// This workaround is needed to make second build as null build.
	if stepDef.ActionName() == "gn" && len(stepManifest.outputs) == 1 && filepath.Base(stepManifest.outputs[0]) == "build.ninja.stamp" {
		stepManifest.outputs = append(stepManifest.outputs, b.path.MaybeFromRelative(ctx, "build.ninja"))
	}

	cmd := &execute.Cmd{
		ID:                      stepDef.String(),
		Desc:                    stepDescription(stepDef),
		ActionName:              stepDef.ActionName(),
		Args:                    b.argTab.InternSlice(stepDef.Args(ctx)),
		RSPFile:                 stepDef.Rspfile(ctx),
		RSPFileContent:          []byte(stepDef.Binding("rspfile_content")),
		CmdHash:                 stepManifest.cmdHash,
		WorkspaceRoot:           b.path.WorkspaceRoot, // use step binding?
		WorkDir:                 b.path.BaseDir,
		Inputs:                  stepInputs(ctx, stepDef),
		ToolInputs:              stepDef.ToolInputs(ctx),
		Outputs:                 stepManifest.outputs,
		EdgeHash:                stepManifest.edgeHash,
		UseSystemInput:          stepDef.Binding("use_system_input") != "",
		Deps:                    stepDef.Binding("deps"),
		Depfile:                 stepDef.Depfile(ctx),
		AuxiliaryLogOutputFiles: stepDef.AuxiliaryLogOutputFiles(ctx),
		AuxiliaryLogOutputDirs:  stepDef.AuxiliaryLogOutputDirs(ctx),

		Restat:        stepDef.Binding("restat") != "",
		RestatContent: stepDef.Binding("restat_content") != "",

		Pure: stepDef.Pure(),

		HashFS: b.hashFS,

		REAPIVersion:  b.reapiclient.APIVersion(),
		Platform:      stepDef.Platform(),
		RemoteWrapper: stepDef.Binding("remote_wrapper"),
		RemoteCommand: stepDef.Binding("remote_command"),
		RemoteInputs:  stepDef.RemoteInputs(),
		// always copy REProxyConfig, allows safe mutation via cmd.action.fix.
		REProxyConfig:   stepDef.REProxyConfig().Copy(),
		CanonicalizeDir: stepDef.Binding("canonicalize_dir") != "false",

		// TODO(b/266518906): enable DoNotCache for read-only client
		// DoNotCache: !b.reCacheEnableWrite,
		SkipCacheLookup: !b.reCacheEnableRead,
		Timeout:         stepTimeout(ctx, stepDef.Binding("timeout")),
		ExecTimeout:     execTimeout(ctx, stepDef.Binding("exec_timeout")),
		ActionSalt:      b.actionSalt,
	}
	if _, ok := cmd.Platform["InputRootAbsolutePath"]; ok {
		// non relocatable request. disable canonicalize dir.
		cmd.CanonicalizeDir = false
	}
	if stepDef.Binding("phony_output") != "" {
		clog.Infof(ctx, "phony_output: no outputs by cmd")
		cmd.Outputs = nil
	}
	if envfile := stepDef.Binding("envfile"); envfile != "" {
		cmd.Env = b.loadEnvfile(ctx, envfile)
	}
	if stepDef.Binding("pool") == "console" {
		// pool=console needs to attach stdin/stdout/stderr
		// so run locally.
		cmd.Platform = nil
		cmd.RemoteWrapper = ""
		cmd.RemoteCommand = ""
		cmd.RemoteInputs = nil
		cmd.REProxyConfig = nil
	} else if experiments.Enabled("gvisor", "Force gVisor") {
		if len(cmd.Platform) == 0 {
			cmd.Platform = map[string]string{}
		}
		cmd.Platform["dockerRuntime"] = "runsc"
	}
	cmd.InitOutputs()

	if experiments.Enabled("oom-score-adj", "Set oom_score_adj=1000 on local exec") {
		score := 1000 // OOM_SCORE_ADJ_MAX. likely to be killed by OOM
		cmd.OOMScoreAdj = &score
	}
	return cmd
}

func stepTimeout(ctx context.Context, d string) time.Duration {
	const defaultTimeout = 1 * time.Hour
	if d == "" {
		return defaultTimeout
	}
	dur, err := time.ParseDuration(d)
	if err != nil {
		clog.Warningf(ctx, "failed to parse duration %q: %v", d, err)
		return defaultTimeout
	}
	return dur
}

func execTimeout(ctx context.Context, d string) time.Duration {
	if d == "" {
		return 0
	}
	dur, err := time.ParseDuration(d)
	if err != nil {
		clog.Warningf(ctx, "failed to parse duration %q: %v", d, err)
		return 0
	}
	return dur
}

func stepInputs(ctx context.Context, stepDef StepDef) []string {
	seen := make(map[string]bool)
	var inputs []string
	for _, in := range stepDef.Inputs(ctx) {
		if seen[in] {
			continue
		}
		seen[in] = true
		inputs = append(inputs, in)
	}
	depsIter, err := stepDef.DepInputs(ctx)
	if err != nil {
		return inputs
	}
	depsIter(func(in string) bool {
		if seen[in] {
			return true
		}
		seen[in] = true
		inputs = append(inputs, in)
		return true
	})
	return inputs
}

func stepDescription(stepDef StepDef) string {
	s := stepDef.Binding("description")
	if s != "" {
		return s
	}
	return stepDef.Binding("command")
}

func validateRemoteActionResult(result *rpb.ActionResult) bool {
	if result == nil {
		return false
	}

	// When the action runs locally, Reproxy doesn't add outputs to the result.
	// Then, the next condition will pass which ends up with retring the same action.
	switch result.GetExecutionMetadata().GetWorker() {
	case reproxyexec.WorkerNameFallback, reproxyexec.WorkerNameRacingLocal, reproxyexec.WorkerNameLocal:
		return true
	}
	if result.ExitCode == 0 && len(result.GetOutputFiles()) == 0 {
		// succeeded result should have at least one output. b/350360391
		return false
	}
	return true
}

type envfile struct {
	once sync.Once
	envs []string
}

func (b *Builder) loadEnvfile(ctx context.Context, fname string) []string {
	env := &envfile{}
	v, loaded := b.envFiles.LoadOrStore(fname, env)
	if loaded {
		env = v.(*envfile)
	}
	env.once.Do(func() {
		// https://ninja-build.org/manual.html#_extra_tools
		// ninja -t msvc -e ENVFILE -- cl.exe <arguments>
		//  Where ENVFILE is a binary file that contains an environment block suitable for CreateProcessA() on Windows (i.e. a series of zero-terminated strings that look like NAME=VALUE, followed by an extra zero terminator).
		buf, err := b.hashFS.ReadFile(ctx, b.path.WorkspaceRoot, b.path.MaybeFromRelative(ctx, fname))
		if err != nil {
			clog.Warningf(ctx, "failed to load envfile %q: %v", fname, err)
			return
		}
		for len(buf) > 0 {
			i := bytes.IndexByte(buf, '\000')
			if i < 0 {
				env.envs = append(env.envs, string(buf))
				break
			}
			e := string(buf[:i])
			buf = buf[i+1:]
			if e != "" {
				env.envs = append(env.envs, e)
			}
		}
		clog.Infof(ctx, "load envfile %q: %d", fname, len(env.envs))
	})
	return env.envs
}
