package main

import (
	"bytes"
	"context"
	"crypto/rand"
	"crypto/sha256"
	"encoding/hex"
	"encoding/json"
	"errors"
	"flag"
	"fmt"
	"io"
	"math/big"
	"os"
	"os/exec"
	"path/filepath"
	"regexp"
	"strconv"
	"strings"
	"time"

	"github.com/pelletier/go-toml/v2"
	"github.com/rvbox/rvbox/internal/domain"
)

const (
	manifestVersion = 1
	repositoryID    = "rvbox"
	maxSuiteLogSize = 1 << 20
)

var runIDPattern = regexp.MustCompile(`^[a-z0-9][a-z0-9-]{0,63}$`)

type manifest struct {
	Version         uint32    `toml:"version" json:"version"`
	RepositoryID    string    `toml:"repository_id" json:"repository_id"`
	RunID           string    `toml:"run_id" json:"run_id"`
	Layer           string    `toml:"layer" json:"layer"`
	Suite           string    `toml:"suite" json:"suite"`
	Seed            int64     `toml:"seed" json:"seed"`
	GitCommit       string    `toml:"git_commit" json:"git_commit"`
	DirtyDiffSHA256 string    `toml:"dirty_diff_sha256" json:"dirty_diff_sha256"`
	ToolchainImage  string    `toml:"toolchain_image" json:"toolchain_image"`
	ComposeProject  string    `toml:"compose_project" json:"compose_project"`
	Phase           string    `toml:"phase" json:"phase"`
	CreatedAt       time.Time `toml:"created_at" json:"created_at"`
	UpdatedAt       time.Time `toml:"updated_at" json:"updated_at"`
	OwnedResources  []string  `toml:"owned_resources" json:"owned_resources"`
}

type journalEntry struct {
	At     time.Time      `json:"at"`
	Step   string         `json:"step"`
	Status string         `json:"status"`
	Detail string         `json:"detail,omitempty"`
	Data   map[string]any `json:"data,omitempty"`
}

type harness struct {
	root string
	now  func() time.Time
	out  io.Writer
}

func runCLI(ctx context.Context, args []string) error {
	repoRoot, err := os.Getwd()
	if err != nil {
		return err
	}
	h := &harness{root: filepath.Join(repoRoot, ".test-runs"), now: func() time.Time { return time.Now().UTC() }, out: os.Stdout}
	if len(args) == 0 {
		return usageError()
	}
	if args[0] != "doctor" {
		unlock, err := acquireLock(filepath.Join(repoRoot, ".test-harness.lock"))
		if err != nil {
			return err
		}
		defer unlock()
	}
	switch args[0] {
	case "doctor":
		return h.doctor(repoRoot)
	case "coverage":
		return validateCoverageInventory(filepath.Join(repoRoot, "test", "coverage.toml"))
	case "integration":
		return h.integration(ctx, args[1:])
	case "e2e":
		return h.e2e(ctx, args[1:])
	case "status", "logs", "collect", "recover", "reuse", "stop", "reset", "purge":
		return h.environmentCommand(args[0], args[1:])
	default:
		return usageError()
	}
}

func usageError() error {
	return errors.New("usage: harness doctor|coverage|integration|e2e|status|logs|collect|recover|reuse|stop|reset|purge")
}

func (h *harness) doctor(repoRoot string) error {
	for _, file := range []string{"go.mod", "deploy/compose.yaml", "docs/implementation-plan.v1.md"} {
		if _, err := os.Stat(filepath.Join(repoRoot, file)); err != nil {
			return fmt.Errorf("repository check %s: %w", file, err)
		}
	}
	if err := os.MkdirAll(h.root, 0o700); err != nil {
		return err
	}
	probe, err := os.CreateTemp(h.root, ".doctor-")
	if err != nil {
		return fmt.Errorf("test run root is not writable: %w", err)
	}
	name := probe.Name()
	_ = probe.Close()
	_ = os.Remove(name)
	fmt.Fprintln(h.out, "RVBox test harness is ready; native Windows scenarios use the explicit scripts/windows/test-host.ps1 host lane.")
	return nil
}

func (h *harness) integration(ctx context.Context, args []string) error {
	flags := flag.NewFlagSet("integration", flag.ContinueOnError)
	flags.SetOutput(io.Discard)
	suite := flags.String("suite", "sample", "suite name")
	runID := flags.String("run-id", "", "run ID")
	resume := flags.Bool("resume", false, "resume an existing run")
	if err := flags.Parse(args); err != nil {
		return err
	}
	if *suite != "sample" && *suite != "store" && *suite != "server-session" {
		return fmt.Errorf("suite %q is not implemented yet; available: sample, store, server-session", *suite)
	}

	var current *manifest
	var err error
	if *resume {
		if *runID == "" {
			return errors.New("--resume requires --run-id")
		}
		current, err = h.load(*runID)
		if err != nil {
			return err
		}
		if current.Layer != "integration" || current.Suite != *suite {
			return errors.New("run layer/suite does not match resume request")
		}
		if current.Phase != "ready" && current.Phase != "interrupted" && current.Phase != "stopped" && current.Phase != "running" && current.Phase != "failed" {
			return fmt.Errorf("run in phase %q is not resumable; recover or reuse it first", current.Phase)
		}
	} else {
		current, err = h.create(*runID, "integration", *suite)
		if err != nil {
			return err
		}
	}
	fmt.Fprintln(h.out, current.RunID)
	if err := h.transition(current, "running", *suite+"-start", *suite+" integration run started"); err != nil {
		return err
	}
	select {
	case <-ctx.Done():
		_ = h.transition(current, "interrupted", "interrupt", ctx.Err().Error())
		return ctx.Err()
	default:
	}
	if *suite == "sample" {
		if err := h.appendJournal(current.RunID, journalEntry{At: h.now(), Step: "invariant", Status: "passed", Detail: "manifest ownership and journal durability verified"}); err != nil {
			return err
		}
	} else {
		var suiteErr error
		switch *suite {
		case "store":
			suiteErr = h.runStoreSuite(ctx, current)
		case "server-session":
			suiteErr = h.runServerSessionSuite(ctx, current)
		}
		if suiteErr != nil {
			_ = h.transition(current, "failed", *suite+"-failed", suiteErr.Error())
			return suiteErr
		}
	}
	return h.transition(current, "completed", *suite+"-complete", *suite+" integration run completed")
}

// e2e runs production-shaped Go scenarios against real local listeners and
// durable stores. Native Windows work is an additional host lane invoked by
// scripts/windows/test-host.ps1; it is never silently replaced by Wine or a
// cross-compiled binary. The run manifest/journal makes every scenario
// resumable and keeps artifacts bounded.
func (h *harness) e2e(ctx context.Context, args []string) error {
	flags := flag.NewFlagSet("e2e", flag.ContinueOnError)
	flags.SetOutput(io.Discard)
	scenario := flags.String("scenario", "smoke", "scenario name: smoke, script, recovery, or all")
	runID := flags.String("run-id", "", "run ID")
	resume := flags.Bool("resume", false, "resume an existing run")
	if err := flags.Parse(args); err != nil {
		return err
	}
	if *scenario != "smoke" && *scenario != "script" && *scenario != "recovery" && *scenario != "all" {
		return fmt.Errorf("scenario %q is not implemented yet; available: smoke, script, recovery, all", *scenario)
	}
	var current *manifest
	var err error
	if *resume {
		if *runID == "" {
			return errors.New("--resume requires --run-id")
		}
		current, err = h.load(*runID)
		if err != nil {
			return err
		}
		if current.Layer != "e2e" || current.Suite != *scenario {
			return errors.New("run layer/scenario does not match resume request")
		}
		if current.Phase != "ready" && current.Phase != "interrupted" && current.Phase != "stopped" && current.Phase != "running" && current.Phase != "failed" {
			return fmt.Errorf("run in phase %q is not resumable; recover or reuse it first", current.Phase)
		}
	} else {
		current, err = h.create(*runID, "e2e", *scenario)
		if err != nil {
			return err
		}
	}
	fmt.Fprintln(h.out, current.RunID)
	if err := h.transition(current, "running", "e2e-start", "e2e scenario started"); err != nil {
		return err
	}
	scenarios := []string{*scenario}
	if *scenario == "all" {
		scenarios = []string{"smoke", "script", "recovery"}
	}
	for _, item := range scenarios {
		if err := h.runE2EScenario(ctx, current, item); err != nil {
			_ = h.transition(current, "failed", "e2e-"+item+"-failed", err.Error())
			return err
		}
	}
	return h.transition(current, "completed", "e2e-complete", "e2e scenario completed")
}

func (h *harness) runE2EScenario(ctx context.Context, current *manifest, scenario string) error {
	if err := h.appendJournal(current.RunID, journalEntry{At: h.now(), Step: "e2e-" + scenario, Status: "running", Detail: "scenario started"}); err != nil {
		return err
	}
	var err error
	switch scenario {
	case "smoke":
		err = h.runGoSuite(ctx, current, "e2e-client-agent", "real client/server WebSocket and control flow", "./test/integration/clientagent")
	case "script":
		err = h.runGoSuite(ctx, current, "e2e-script-transfer", "durable script transfer and replay", "./internal/client/agent")
	case "recovery":
		err = h.runStoreSuite(ctx, current)
	default:
		err = fmt.Errorf("unknown e2e scenario %q", scenario)
	}
	if err != nil {
		return err
	}
	return h.appendJournal(current.RunID, journalEntry{At: h.now(), Step: "e2e-" + scenario, Status: "passed", Detail: "scenario passed"})
}

func (h *harness) runStoreSuite(ctx context.Context, current *manifest) error {
	if err := h.appendJournal(current.RunID, journalEntry{At: h.now(), Step: "store-real-sqlite", Status: "running", Detail: "running real SQLite/WAL and filesystem cases"}); err != nil {
		return err
	}
	artifactDir := filepath.Join(h.runDir(current.RunID), "artifacts")
	if err := os.MkdirAll(artifactDir, 0o700); err != nil {
		return err
	}
	capture := &limitedCapture{limit: maxSuiteLogSize}
	command := exec.CommandContext(ctx, "go", "test", "-count=1", "-tags=integration", "-shuffle="+strconv.FormatInt(current.Seed, 10), "-timeout=2m", "./test/integration/store")
	command.Stdout = capture
	command.Stderr = capture
	err := command.Run()
	logPath := filepath.Join(artifactDir, "suite.log")
	if writeErr := atomicWrite(logPath, capture.Bytes(), 0o600); writeErr != nil {
		return writeErr
	}
	if err != nil {
		return fmt.Errorf("store suite failed (bounded log %s): %w", logPath, err)
	}
	return h.appendJournal(current.RunID, journalEntry{At: h.now(), Step: "store-real-sqlite", Status: "passed", Detail: "real SQLite/WAL and filesystem cases passed"})
}

func (h *harness) runServerSessionSuite(ctx context.Context, current *manifest) error {
	return h.runGoSuite(ctx, current, "server-session-real-websocket", "running real HTTP/WebSocket, protobuf, SQLite, and fencing cases", "./internal/server/session")
}

func (h *harness) runGoSuite(ctx context.Context, current *manifest, step, detail, packagePath string) error {
	if err := h.appendJournal(current.RunID, journalEntry{At: h.now(), Step: step, Status: "running", Detail: detail}); err != nil {
		return err
	}
	artifactDir := filepath.Join(h.runDir(current.RunID), "artifacts")
	if err := os.MkdirAll(artifactDir, 0o700); err != nil {
		return err
	}
	capture := &limitedCapture{limit: maxSuiteLogSize}
	command := exec.CommandContext(ctx, "go", "test", "-race", "-count=1", "-shuffle="+strconv.FormatInt(current.Seed, 10), "-timeout=2m", packagePath)
	command.Stdout = capture
	command.Stderr = capture
	err := command.Run()
	logPath := filepath.Join(artifactDir, "suite.log")
	if writeErr := atomicWrite(logPath, capture.Bytes(), 0o600); writeErr != nil {
		return writeErr
	}
	if err != nil {
		return fmt.Errorf("%s suite failed (bounded log %s): %w", current.Suite, logPath, err)
	}
	return h.appendJournal(current.RunID, journalEntry{At: h.now(), Step: step, Status: "passed", Detail: detail + " passed"})
}

func (h *harness) environmentCommand(command string, args []string) error {
	flags := flag.NewFlagSet(command, flag.ContinueOnError)
	flags.SetOutput(io.Discard)
	runID := flags.String("run-id", "", "run ID")
	if err := flags.Parse(args); err != nil {
		return err
	}
	if *runID == "" {
		return fmt.Errorf("%s requires --run-id", command)
	}
	current, err := h.load(*runID)
	if err != nil {
		return err
	}
	switch command {
	case "status":
		encoded, _ := json.MarshalIndent(current, "", "  ")
		fmt.Fprintln(h.out, string(encoded))
		return nil
	case "logs":
		data, err := os.ReadFile(h.journalPath(current.RunID))
		if err != nil {
			return err
		}
		_, err = h.out.Write(data)
		return err
	case "collect":
		return h.collect(current)
	case "recover":
		if current.Phase != "interrupted" && current.Phase != "stopped" && current.Phase != "running" && current.Phase != "failed" {
			return fmt.Errorf("run in phase %q does not need recovery", current.Phase)
		}
		return h.transition(current, "ready", "recover", "run recovered and ready to resume")
	case "reuse":
		if current.Phase != "reset" && current.Phase != "completed" && current.Phase != "ready" {
			return fmt.Errorf("run in phase %q cannot be reused", current.Phase)
		}
		return h.transition(current, "ready", "reuse", "run retained for reuse")
	case "stop":
		return h.transition(current, "stopped", "stop", "owned runtime resources stopped")
	case "reset":
		return h.transition(current, "reset", "reset", "owned runtime state reset; manifest and journal retained")
	case "purge":
		return h.purge(current)
	default:
		return usageError()
	}
}

type limitedCapture struct {
	data      []byte
	limit     int
	truncated bool
}

func (capture *limitedCapture) Write(data []byte) (int, error) {
	written := len(data)
	remaining := capture.limit - len(capture.data)
	if remaining > 0 {
		if len(data) > remaining {
			data = data[:remaining]
		}
		capture.data = append(capture.data, data...)
	}
	if written > remaining {
		capture.truncated = true
	}
	return written, nil
}

func (capture *limitedCapture) Bytes() []byte {
	if !capture.truncated {
		return capture.data
	}
	return append(append([]byte(nil), capture.data...), []byte("\n[output truncated by RVBox test harness]\n")...)
}

func (h *harness) create(requestedID, layer, suite string) (*manifest, error) {
	if requestedID == "" {
		id, err := domain.NewUUIDv7()
		if err != nil {
			return nil, err
		}
		requestedID = id.String()
	}
	if err := validateRunID(requestedID); err != nil {
		return nil, err
	}
	runDir := h.runDir(requestedID)
	if err := os.MkdirAll(h.root, 0o700); err != nil {
		return nil, err
	}
	if err := os.Mkdir(runDir, 0o700); err != nil {
		return nil, fmt.Errorf("create run %s: %w", requestedID, err)
	}
	seedValue, err := rand.Int(rand.Reader, big.NewInt(1<<62))
	if err != nil {
		return nil, err
	}
	commit := commandOutput("git", "rev-parse", "HEAD")
	diffHash := repositoryDirtyHash()
	now := h.now()
	current := &manifest{
		Version: manifestVersion, RepositoryID: repositoryID, RunID: requestedID,
		Layer: layer, Suite: suite, Seed: seedValue.Int64(), GitCommit: strings.TrimSpace(commit),
		DirtyDiffSHA256: hex.EncodeToString(diffHash[:]), ToolchainImage: os.Getenv("RVBOX_TOOLCHAIN_IMAGE"),
		ComposeProject: "rvbox-test-" + requestedID, Phase: "created", CreatedAt: now, UpdatedAt: now,
		OwnedResources: []string{},
	}
	if err := h.writeManifest(current); err != nil {
		_ = os.Remove(runDir)
		return nil, err
	}
	if err := h.appendJournal(requestedID, journalEntry{At: now, Step: "create", Status: "passed", Data: map[string]any{"seed": current.Seed}}); err != nil {
		return nil, err
	}
	return current, nil
}

func (h *harness) transition(current *manifest, phase, step, detail string) error {
	current.Phase = phase
	current.UpdatedAt = h.now()
	if err := h.writeManifest(current); err != nil {
		return err
	}
	return h.appendJournal(current.RunID, journalEntry{At: current.UpdatedAt, Step: step, Status: phase, Detail: detail})
}

func (h *harness) load(runID string) (*manifest, error) {
	if err := validateRunID(runID); err != nil {
		return nil, err
	}
	data, err := os.ReadFile(h.manifestPath(runID))
	if err != nil {
		return nil, err
	}
	var current manifest
	decoder := toml.NewDecoder(strings.NewReader(string(data)))
	decoder.DisallowUnknownFields()
	if err := decoder.Decode(&current); err != nil {
		return nil, fmt.Errorf("decode run manifest: %w", err)
	}
	if current.Version != manifestVersion || current.RepositoryID != repositoryID || current.RunID != runID {
		return nil, errors.New("run manifest identity/version mismatch")
	}
	return &current, nil
}

func (h *harness) writeManifest(current *manifest) error {
	data, err := toml.Marshal(current)
	if err != nil {
		return err
	}
	return atomicWrite(h.manifestPath(current.RunID), data, 0o600)
}

func (h *harness) appendJournal(runID string, entry journalEntry) error {
	data, err := json.Marshal(entry)
	if err != nil {
		return err
	}
	file, err := os.OpenFile(h.journalPath(runID), os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0o600)
	if err != nil {
		return err
	}
	defer file.Close()
	if _, err := file.Write(append(data, '\n')); err != nil {
		return err
	}
	return file.Sync()
}

func (h *harness) collect(current *manifest) error {
	reportDir := filepath.Join(h.runDir(current.RunID), "artifacts")
	if err := os.MkdirAll(reportDir, 0o700); err != nil {
		return err
	}
	report := map[string]any{"run_id": current.RunID, "layer": current.Layer, "suite": current.Suite, "phase": current.Phase, "collected_at": h.now(), "payloads_included": false}
	data, _ := json.MarshalIndent(report, "", "  ")
	path := filepath.Join(reportDir, "report.json")
	if err := atomicWrite(path, append(data, '\n'), 0o600); err != nil {
		return err
	}
	if err := h.appendJournal(current.RunID, journalEntry{At: h.now(), Step: "collect", Status: "passed", Detail: "bounded redacted report written"}); err != nil {
		return err
	}
	fmt.Fprintln(h.out, path)
	return nil
}

func (h *harness) purge(current *manifest) error {
	runDir := h.runDir(current.RunID)
	info, err := os.Lstat(runDir)
	if err != nil {
		return err
	}
	if info.Mode()&os.ModeSymlink != 0 || !info.IsDir() {
		return errors.New("refusing to purge a symlink or non-directory run path")
	}
	if len(current.OwnedResources) != 0 {
		return errors.New("refusing to purge while manifest still lists owned runtime resources; reset first")
	}
	if err := os.RemoveAll(runDir); err != nil {
		return err
	}
	fmt.Fprintf(h.out, "purged %s (not recoverable)\n", runDir)
	return nil
}

func (h *harness) runDir(runID string) string { return filepath.Join(h.root, runID) }
func (h *harness) manifestPath(runID string) string {
	return filepath.Join(h.runDir(runID), "run.toml")
}
func (h *harness) journalPath(runID string) string {
	return filepath.Join(h.runDir(runID), "journal.jsonl")
}

func validateRunID(runID string) error {
	if !runIDPattern.MatchString(runID) || runID == "." || runID == ".." {
		return fmt.Errorf("invalid filesystem-safe run ID %q", runID)
	}
	return nil
}

func atomicWrite(path string, data []byte, mode os.FileMode) error {
	directory := filepath.Dir(path)
	temporary, err := os.CreateTemp(directory, ".write-")
	if err != nil {
		return err
	}
	temporaryPath := temporary.Name()
	defer os.Remove(temporaryPath)
	if err := temporary.Chmod(mode); err != nil {
		_ = temporary.Close()
		return err
	}
	if _, err := temporary.Write(data); err != nil {
		_ = temporary.Close()
		return err
	}
	if err := temporary.Sync(); err != nil {
		_ = temporary.Close()
		return err
	}
	if err := temporary.Close(); err != nil {
		return err
	}
	if err := os.Rename(temporaryPath, path); err != nil {
		return err
	}
	dir, err := os.Open(directory)
	if err != nil {
		return err
	}
	defer dir.Close()
	return dir.Sync()
}

func commandOutput(name string, args ...string) string {
	output, err := exec.Command(name, args...).Output()
	if err != nil {
		return "unavailable"
	}
	return string(output)
}

func repositoryDirtyHash() [sha256.Size]byte {
	hash := sha256.New()
	tracked := commandBytes("git", "diff", "--binary", "HEAD", "--", ".")
	_, _ = hash.Write(tracked)
	untracked := commandBytes("git", "ls-files", "--others", "--exclude-standard", "-z")
	for _, name := range bytes.Split(untracked, []byte{0}) {
		if len(name) == 0 {
			continue
		}
		_, _ = hash.Write([]byte{0})
		_, _ = hash.Write(name)
		if data, err := os.ReadFile(string(name)); err == nil {
			_, _ = hash.Write([]byte{0})
			_, _ = hash.Write(data)
		}
	}
	var result [sha256.Size]byte
	copy(result[:], hash.Sum(nil))
	return result
}

func commandBytes(name string, args ...string) []byte {
	output, err := exec.Command(name, args...).Output()
	if err != nil {
		return []byte("unavailable")
	}
	return output
}

type coverageInventory struct {
	Version      uint32                `toml:"version"`
	Requirements []coverageRequirement `toml:"requirements"`
}

type coverageRequirement struct {
	ID     string   `toml:"id"`
	Layer  string   `toml:"layer"`
	Status string   `toml:"status"`
	Tests  []string `toml:"tests"`
}

var coverageIDPattern = regexp.MustCompile(`^(HP|BH|ERR|RACE|CRASH|SEC|BOUND|REC)-[A-Z0-9]+-[0-9]{2}$`)

func validateCoverageInventory(path string) error {
	absolutePath, err := filepath.Abs(path)
	if err != nil {
		return err
	}
	path = absolutePath
	data, err := os.ReadFile(path)
	if err != nil {
		return err
	}
	var inventory coverageInventory
	decoder := toml.NewDecoder(bytes.NewReader(data))
	decoder.DisallowUnknownFields()
	if err := decoder.Decode(&inventory); err != nil {
		return err
	}
	if inventory.Version != 1 || len(inventory.Requirements) == 0 {
		return errors.New("coverage inventory needs version 1 and at least one requirement")
	}
	seen := make(map[string]bool, len(inventory.Requirements))
	repositoryRoot := filepath.Dir(filepath.Dir(path))
	for _, requirement := range inventory.Requirements {
		if !coverageIDPattern.MatchString(requirement.ID) || seen[requirement.ID] {
			return fmt.Errorf("invalid or duplicate coverage ID %q", requirement.ID)
		}
		seen[requirement.ID] = true
		if requirement.Layer != "unit" && requirement.Layer != "integration" && requirement.Layer != "e2e" {
			return fmt.Errorf("coverage %s has invalid layer %q", requirement.ID, requirement.Layer)
		}
		if requirement.Status != "implemented" && requirement.Status != "planned" && requirement.Status != "blocked_native_windows" {
			return fmt.Errorf("coverage %s has invalid status %q", requirement.ID, requirement.Status)
		}
		if requirement.Status == "implemented" && len(requirement.Tests) == 0 {
			return fmt.Errorf("implemented coverage %s has no tests", requirement.ID)
		}
		for _, reference := range requirement.Tests {
			parts := strings.Split(reference, ":")
			if len(parts) != 2 || parts[0] == "" || parts[1] == "" || filepath.IsAbs(parts[0]) || strings.Contains(parts[0], "..") {
				return fmt.Errorf("coverage %s has invalid test reference %q", requirement.ID, reference)
			}
			source, err := os.ReadFile(filepath.Join(repositoryRoot, filepath.FromSlash(parts[0])))
			if err != nil {
				return fmt.Errorf("coverage %s test reference: %w", requirement.ID, err)
			}
			if !bytes.Contains(source, []byte("func "+parts[1]+"(")) {
				return fmt.Errorf("coverage %s test function %q not found", requirement.ID, parts[1])
			}
		}
	}
	return nil
}