package updater

import (
	"context"
	"fmt"
	"strings"
	"time"

	agentmodule "github.com/dbledeez/panel/agent/internal/module"
	"github.com/dbledeez/panel/agent/internal/runtime"
	modulepkg "github.com/dbledeez/panel/pkg/module"
)

// SteamCMDProvider runs `steamcmd +force_install_dir <path> +login
// anonymous +app_update <appid> [-beta <branch>] validate +quit` in a
// one-shot sidecar container that mounts the target instance's volumes.
// The sidecar writes game files into the same Docker volumes the main
// container reads from, so "update then start" just works.
//
// Preconditions:
//   - Target instance's container must NOT be running (Steam holds file
//     locks that conflict with a live server). Error clearly otherwise.
//   - Manifest must declare at least one volume; install_path resolves
//     to spec.InstallPath → BrowseableRoot → first volume's container path.
type SteamCMDProvider struct{}

// Name identifies this provider kind in logs / manifest.
func (SteamCMDProvider) Name() string { return "steamcmd" }

// sidecarImage is the official Valve-maintained SteamCMD image. Its
// ENTRYPOINT is `steamcmd`, so we pass steamcmd's `+...` flags as Cmd.
const sidecarImage = "steamcmd/steamcmd:latest"

// redactSteamPassword replaces a password in a cmdline arg slice with
// "[REDACTED]" so the Console tab never echoes it. Used before logging
// steamcmd argv.
func redactSteamPassword(args []string, password string) []string {
	if password == "" {
		return args
	}
	out := make([]string, len(args))
	for i, a := range args {
		if a == password {
			out[i] = "[REDACTED]"
			continue
		}
		out[i] = a
	}
	return out
}

// redactPasswordLine strips the password substring from a log line if it
// ever appears (e.g. SteamCMD echoing `+login user PASS` back). Returns
// the original string when password is empty so anonymous/public flows
// are zero-cost.
func redactPasswordLine(line, password string) string {
	if password == "" || len(password) < 4 {
		return line
	}
	if !strings.Contains(line, password) {
		return line
	}
	return strings.ReplaceAll(line, password, "[REDACTED]")
}

func (SteamCMDProvider) Update(ctx context.Context, uc *Context, spec *modulepkg.UpdateProvider) error {
	if spec.AppID == "" {
		return fmt.Errorf("steamcmd provider: app_id is required")
	}

	// Refuse if the main container is still running — Steam locks files.
	mainName := "panel-" + uc.InstanceID
	if state, err := uc.Runtime.InspectByName(ctx, mainName); err == nil && state.Status == "running" {
		return fmt.Errorf("stop the instance first — container %q is running; SteamCMD conflicts with a live server", mainName)
	}

	installPath := spec.InstallPath
	if installPath == "" {
		installPath = uc.BrowseableRoot
	}
	if installPath == "" {
		return fmt.Errorf("steamcmd provider: install_path missing and module has no browseable_root/volumes to default from")
	}

	// Mount the same volumes as the target instance so SteamCMD writes
	// where the main container will later read.
	volumes := agentmodule.ResolveVolumes(uc.Manifest, uc.InstanceID, uc.DataPath)
	if len(volumes) == 0 {
		return fmt.Errorf("steamcmd provider: module declares no volumes to mount")
	}

	// Platform override MUST come before +login — SteamCMD evaluates its
	// forced-platform state at login time, not at app_update time. Used for
	// apps that ship only a Windows depot (run via Wine on Linux hosts).
	args := []string{}
	if spec.Platform != "" {
		args = append(args, "+@sSteamCmdForcePlatformType", spec.Platform)
	}
	args = append(args, "+force_install_dir", installPath)

	// Non-anonymous Steam login for paid apps (DayZ, Arma). If the module
	// declared requires_steam_login and the controller forwarded creds,
	// use them. Otherwise fall back to anonymous (most free-to-download
	// dedicated servers work anonymously).
	//
	// CRITICAL for UX: pass ONLY the username when possible. SteamCMD's
	// `+login <user>` uses the cached refresh token from config.vdf
	// (persisted in panel-steamcmd-auth) — no Steam Guard push, no
	// password round-trip. Passing `+login <user> <password>` forces a
	// fresh password auth every time, which triggers a 2FA push on every
	// call even when a perfectly valid cached token is already on disk.
	//
	// First-ever login ceremony happens in the controller (steamauth.go)
	// with the full password+guard flow to prime the cache. After that,
	// this path rides the cache. If the cache is stale/expired, SteamCMD
	// exits non-zero — the retry loop below re-runs which will hit the
	// same error; the operator then clicks Update, which the controller
	// can short-circuit to re-run the login modal (the `steam_login_required`
	// response path).
	needsLogin := spec.RequiresSteamLogin && uc.SteamUsername != ""
	if needsLogin {
		args = append(args, "+login", uc.SteamUsername)
	} else {
		args = append(args, "+login", "anonymous")
	}
	updateArgs := []string{"+app_update", spec.AppID}
	if spec.Beta != "" {
		updateArgs = append(updateArgs, "-beta", spec.Beta)
	}
	if !spec.SkipValidate {
		updateArgs = append(updateArgs, "validate")
	}
	args = append(args, updateArgs...)
	args = append(args, "+quit")

	uc.Log(fmt.Sprintf("steamcmd: image=%s install_path=%s app_id=%s beta=%s", sidecarImage, installPath, spec.AppID, spec.Beta))
	uc.Log(fmt.Sprintf("steamcmd argv: %v", redactSteamPassword(args, uc.SteamPassword)))

	// SteamCMD is notoriously flaky on first invocation — exit 8 ("missing
	// configuration"), exit 2 (generic "retry later"), and Steam auth races
	// are all recoverable by simply running the same command again. AMP,
	// LinuxGSM, and Valve's own Steam client all retry on these codes. We
	// mirror that behaviour so operators don't have to click Update twice.
	const maxAttempts = 4
	var lastExit int
	var ranSuccessfully bool
	for attempt := 1; attempt <= maxAttempts; attempt++ {
		exitCode, err := runSteamCMDOnce(ctx, uc, sidecarImage, args, volumes, attempt)
		lastExit = exitCode
		if err == nil && exitCode == 0 {
			uc.Log(fmt.Sprintf("steamcmd: completed successfully (app_id=%s, attempts=%d)", spec.AppID, attempt))
			ranSuccessfully = true
			break
		}
		// Transient exit codes SteamCMD is known to recover from. Anything
		// else we surface immediately (missing disk space, bad app id, etc.).
		transient := err == nil && (exitCode == 2 || exitCode == 5 || exitCode == 8)
		if err != nil {
			return err
		}
		if !transient || attempt == maxAttempts {
			break
		}
		backoff := time.Duration(attempt*attempt*3) * time.Second // 3s, 12s, 27s
		uc.Log(fmt.Sprintf("steamcmd: exit %d — transient, retrying in %s (attempt %d/%d)", exitCode, backoff, attempt+1, maxAttempts))
		select {
		case <-ctx.Done():
			return ctx.Err()
		case <-time.After(backoff):
		}
	}

	// Finalize: SteamCMD with `+force_install_dir <p>` stages downloads
	// at <p>/steamapps/downloading/<appid>/ and atomically renames into
	// <p>/ on success. When SteamCMD exits with state 0x602 (often after
	// concurrent runs interrupt finalization, or a `validate` pass races
	// the move) the bytes are on disk but never get renamed — operator
	// sees an empty install dir and an exit-8 error from the panel.
	//
	// This step runs unconditionally after the retry loop. If the staging
	// dir is empty or absent (the happy path), it's a cheap no-op. If it
	// has content, we cp -a it into place and the install completes.
	finalized, ferr := finalizeStagingDir(ctx, uc, installPath, spec.AppID, volumes)
	if ferr != nil {
		uc.Log(fmt.Sprintf("steamcmd: finalize check failed: %s (continuing anyway)", ferr.Error()))
	} else if finalized {
		uc.Log("steamcmd: recovered staged install (state 0x602 workaround)")
		return nil
	}

	if ranSuccessfully {
		return nil
	}
	return fmt.Errorf("steamcmd exited %d after %d attempt(s)", lastExit, maxAttempts)
}

// finalizeStagingDir checks for a stranded SteamCMD staging directory
// at <installPath>/steamapps/downloading/<appid>/ and, if present and
// non-empty, moves its contents into <installPath>/. Runs as a one-shot
// alpine sidecar with the same volume mounts as the SteamCMD run so
// it has access to the install path. Returns true if a recovery move
// actually happened, false if there was nothing to do.
//
// The script is intentionally defensive:
//   - mv is preferred over cp+rm because it's atomic on the same FS.
//   - If both source and destination have entries with the same name,
//     mv -f overwrites (rare; happens when steamcmd partially renamed
//     before dying).
//   - We exit 0 on "no staging dir" so this is a no-op for the happy
//     path.
func finalizeStagingDir(ctx context.Context, uc *Context, installPath, appID string, volumes []runtime.VolumeSpec) (bool, error) {
	const stagingMarker = "/__staging__"
	script := fmt.Sprintf(`set -e
DL=%q/steamapps/downloading/%s
DEST=%q
if [ ! -d "$DL" ] || [ -z "$(ls -A "$DL" 2>/dev/null)" ]; then
  echo "no-staging"
  exit 0
fi
echo "finalizing $DL -> $DEST"
mkdir -p "$DEST"
# mv every top-level entry; -f overwrites partial renames.
for f in "$DL"/* "$DL"/.[!.]* "$DL"/..?*; do
  [ -e "$f" ] || continue
  mv -f "$f" "$DEST/" 2>&1 || cp -a "$f" "$DEST/" && rm -rf "$f"
done
rm -rf "$DL"
touch %q
echo "finalized"
`, installPath, appID, installPath, installPath+stagingMarker)

	sidecarSpec := runtime.InstanceSpec{
		InstanceID:    fmt.Sprintf("%s-steamcmd-finalize", uc.InstanceID),
		IsSidecar:     true,
		Image:         "alpine:latest",
		Command:       []string{"sh", "-c", script},
		Volumes:       volumes,
		RestartPolicy: "no",
	}
	contID, err := uc.Runtime.Create(ctx, sidecarSpec)
	if err != nil {
		return false, fmt.Errorf("create finalize sidecar: %w", err)
	}
	defer func() {
		rmCtx, cancel := context.WithTimeout(context.Background(), 15*time.Second)
		defer cancel()
		_ = uc.Runtime.Remove(rmCtx, contID)
	}()
	if err := uc.Runtime.Start(ctx, contID); err != nil {
		return false, fmt.Errorf("start finalize sidecar: %w", err)
	}
	logCtx, cancelLogs := context.WithCancel(ctx)
	defer cancelLogs()
	logDone := make(chan struct{})
	var lastLine string
	go func() {
		defer close(logDone)
		_ = uc.Runtime.StreamLogs(logCtx, contID, func(_ runtime.LogStream, line string, _ time.Time) {
			lastLine = strings.TrimSpace(line)
			uc.Log("finalize: " + lastLine)
		})
	}()
	exitCode, err := uc.Runtime.Wait(ctx, contID)
	cancelLogs()
	<-logDone
	if err != nil {
		return false, fmt.Errorf("wait finalize sidecar: %w", err)
	}
	if exitCode != 0 {
		return false, fmt.Errorf("finalize sidecar exit %d", exitCode)
	}
	return lastLine == "finalized", nil
}

// runSteamCMDOnce is a single run of the steamcmd sidecar; called in a loop
// by the retry wrapper. Returns the container's exit code on clean
// lifecycle (even non-zero) or an error on infrastructure failure.
func runSteamCMDOnce(ctx context.Context, uc *Context, image string, args []string, volumes []runtime.VolumeSpec, attempt int) (int, error) {
	sidecarID := fmt.Sprintf("%s-steamcmd-%d", uc.InstanceID, attempt)
	// Mount the panel-wide SteamCMD auth volume at /root/.local/share/Steam
	// (the real data dir of the steamcmd:latest image — NOT /root/Steam).
	// This persists config/config.vdf (login refresh token) + ssfn sentry,
	// which lets subsequent `+login <user>` runs skip the 2FA push. Anon
	// logins ignore this dir — no harm.
	volumesWithAuth := append([]runtime.VolumeSpec(nil), volumes...)
	volumesWithAuth = append(volumesWithAuth, runtime.VolumeSpec{
		VolumeName:    "panel-steamcmd-auth",
		ContainerPath: "/root/.local/share/Steam",
		Type:          "volume",
	})
	sidecarSpec := runtime.InstanceSpec{
		InstanceID:    sidecarID,
		IsSidecar:     true,
		Image:         image,
		Command:       args,
		Volumes:       volumesWithAuth,
		RestartPolicy: "no",
		// Docker 29.4+ default seccomp ENOSYS's a syscall the 32-bit
		// Steam runtime needs ("CreateBoundSocket error 38"). Older
		// Docker (29.1.x on princess/ivy) doesn't filter it. Unconfine
		// for the sidecar so install/validate works across hosts.
		SecurityOpts: []string{"seccomp=unconfined"},
	}
	contID, err := uc.Runtime.Create(ctx, sidecarSpec)
	if err != nil {
		return 0, fmt.Errorf("create sidecar: %w", err)
	}
	defer func() {
		rmCtx, cancel := context.WithTimeout(context.Background(), 15*time.Second)
		defer cancel()
		_ = uc.Runtime.Remove(rmCtx, contID)
	}()
	if err := uc.Runtime.Start(ctx, contID); err != nil {
		return 0, fmt.Errorf("start sidecar: %w", err)
	}
	logCtx, cancelLogs := context.WithCancel(ctx)
	defer cancelLogs()
	logDone := make(chan struct{})
	go func() {
		defer close(logDone)
		_ = uc.Runtime.StreamLogs(logCtx, contID, func(_ runtime.LogStream, line string, _ time.Time) {
			uc.Log(redactPasswordLine(line, uc.SteamPassword))
		})
	}()
	exitCode, err := uc.Runtime.Wait(ctx, contID)
	cancelLogs()
	<-logDone
	if err != nil {
		return 0, fmt.Errorf("wait sidecar: %w", err)
	}
	return exitCode, nil
}