package daemon

import (
	"context"
	"errors"
	"fmt"
	"os"
	"path/filepath"
	"strings"

	"banger/internal/guest"
	"banger/internal/model"
	"banger/internal/system"
)

const (
	workDiskGitConfigRelativePath       = ".gitconfig"
	workDiskOpencodeAuthDirRelativePath = ".local/share/opencode"
	workDiskOpencodeAuthRelativePath    = workDiskOpencodeAuthDirRelativePath + "/auth.json"
	workDiskClaudeAuthDirRelativePath   = ".claude"
	workDiskClaudeAuthRelativePath      = workDiskClaudeAuthDirRelativePath + "/.credentials.json"
	workDiskPiAuthDirRelativePath       = ".pi/agent"
	workDiskPiAuthRelativePath          = workDiskPiAuthDirRelativePath + "/auth.json"
	hostGlobalGitIdentitySource         = "git config --global"
	hostOpencodeAuthDefaultDisplayPath  = "~/" + workDiskOpencodeAuthRelativePath
	hostClaudeAuthDefaultDisplayPath    = "~/" + workDiskClaudeAuthRelativePath
	hostPiAuthDefaultDisplayPath        = "~/" + workDiskPiAuthRelativePath
)

type gitIdentity struct {
	Name  string
	Email string
}

func (d *Daemon) ensureAuthorizedKeyOnWorkDisk(ctx context.Context, vm *model.VMRecord, image model.Image, prep workDiskPreparation) error {
	fingerprint, err := guest.AuthorizedPublicKeyFingerprint(d.config.SSHKeyPath)
	if err != nil {
		return fmt.Errorf("derive authorized ssh key fingerprint: %w", err)
	}
	if prep.ClonedFromSeed && image.SeededSSHPublicKeyFingerprint != "" && image.SeededSSHPublicKeyFingerprint == fingerprint {
		vmCreateStage(ctx, "prepare_work_disk", "using seeded SSH access")
		return nil
	}
	publicKey, err := guest.AuthorizedPublicKey(d.config.SSHKeyPath)
	if err != nil {
		return fmt.Errorf("derive authorized ssh key: %w", err)
	}
	vmCreateStage(ctx, "prepare_work_disk", "repairing SSH access on work disk")
	workMount, cleanupWork, err := system.MountTempDir(ctx, d.runner, vm.Runtime.WorkDiskPath, false)
	if err != nil {
		return err
	}
	defer cleanupWork()

	if err := d.flattenNestedWorkHome(ctx, workMount); err != nil {
		return err
	}

	sshDir := filepath.Join(workMount, ".ssh")
	if _, err := d.runner.RunSudo(ctx, "mkdir", "-p", sshDir); err != nil {
		return err
	}
	if _, err := d.runner.RunSudo(ctx, "chmod", "700", sshDir); err != nil {
		return err
	}

	authorizedKeysPath := filepath.Join(sshDir, "authorized_keys")
	existing, err := d.runner.RunSudo(ctx, "cat", authorizedKeysPath)
	if err != nil {
		existing = nil
	}
	merged := mergeAuthorizedKey(existing, publicKey)

	tmpFile, err := os.CreateTemp("", "banger-authorized-keys-*")
	if err != nil {
		return err
	}
	tmpPath := tmpFile.Name()
	if _, err := tmpFile.Write(merged); err != nil {
		_ = tmpFile.Close()
		_ = os.Remove(tmpPath)
		return err
	}
	if err := tmpFile.Close(); err != nil {
		_ = os.Remove(tmpPath)
		return err
	}
	defer os.Remove(tmpPath)

	if _, err := d.runner.RunSudo(ctx, "install", "-m", "600", tmpPath, authorizedKeysPath); err != nil {
		return err
	}
	if prep.ClonedFromSeed && image.Managed {
		vmCreateStage(ctx, "prepare_work_disk", "refreshing managed work seed")
		if err := d.refreshManagedWorkSeedFingerprint(ctx, image, fingerprint); err != nil {
			return err
		}
	}
	return nil
}

func (d *Daemon) ensureGitIdentityOnWorkDisk(ctx context.Context, vm *model.VMRecord) error {
	runner := d.runner
	if runner == nil {
		runner = system.NewRunner()
	}

	identity, err := resolveHostGlobalGitIdentity(ctx, runner)
	if err != nil {
		d.warnGitIdentitySyncSkipped(*vm, hostGlobalGitIdentitySource, err)
		return nil
	}

	vmCreateStage(ctx, "prepare_work_disk", "syncing git identity")
	workMount, cleanupWork, err := system.MountTempDir(ctx, runner, vm.Runtime.WorkDiskPath, false)
	if err != nil {
		return err
	}
	defer cleanupWork()

	if err := d.flattenNestedWorkHome(ctx, workMount); err != nil {
		return err
	}

	return writeGitIdentity(ctx, runner, filepath.Join(workMount, workDiskGitConfigRelativePath), identity)
}

func (d *Daemon) ensureOpencodeAuthOnWorkDisk(ctx context.Context, vm *model.VMRecord) error {
	return d.ensureAuthFileOnWorkDisk(
		ctx,
		vm,
		"syncing opencode auth",
		hostOpencodeAuthDefaultDisplayPath,
		resolveHostOpencodeAuthPath,
		workDiskOpencodeAuthRelativePath,
		d.warnOpencodeAuthSyncSkipped,
	)
}

func (d *Daemon) ensureClaudeAuthOnWorkDisk(ctx context.Context, vm *model.VMRecord) error {
	return d.ensureAuthFileOnWorkDisk(
		ctx,
		vm,
		"syncing claude auth",
		hostClaudeAuthDefaultDisplayPath,
		resolveHostClaudeAuthPath,
		workDiskClaudeAuthRelativePath,
		d.warnClaudeAuthSyncSkipped,
	)
}

func (d *Daemon) ensurePiAuthOnWorkDisk(ctx context.Context, vm *model.VMRecord) error {
	return d.ensureAuthFileOnWorkDisk(
		ctx,
		vm,
		"syncing pi auth",
		hostPiAuthDefaultDisplayPath,
		resolveHostPiAuthPath,
		workDiskPiAuthRelativePath,
		d.warnPiAuthSyncSkipped,
	)
}

func (d *Daemon) ensureAuthFileOnWorkDisk(ctx context.Context, vm *model.VMRecord, stageDetail, defaultDisplayPath string, resolveHostPath func() (string, error), guestRelativePath string, warn func(model.VMRecord, string, error)) error {
	hostAuthPath, err := resolveHostPath()
	if err != nil {
		warn(*vm, defaultDisplayPath, err)
		return nil
	}
	authData, err := os.ReadFile(hostAuthPath)
	if err != nil {
		warn(*vm, hostAuthPath, err)
		return nil
	}

	runner := d.runner
	if runner == nil {
		runner = system.NewRunner()
	}

	vmCreateStage(ctx, "prepare_work_disk", stageDetail)
	workMount, cleanupWork, err := system.MountTempDir(ctx, runner, vm.Runtime.WorkDiskPath, false)
	if err != nil {
		return err
	}
	defer cleanupWork()

	if err := d.flattenNestedWorkHome(ctx, workMount); err != nil {
		return err
	}

	authDir := filepath.Join(workMount, filepath.Dir(guestRelativePath))
	if _, err := runner.RunSudo(ctx, "mkdir", "-p", authDir); err != nil {
		return err
	}
	authPath := filepath.Join(workMount, guestRelativePath)

	tmpFile, err := os.CreateTemp("", "banger-auth-*")
	if err != nil {
		return err
	}
	tmpPath := tmpFile.Name()
	if _, err := tmpFile.Write(authData); err != nil {
		_ = tmpFile.Close()
		_ = os.Remove(tmpPath)
		return err
	}
	if err := tmpFile.Close(); err != nil {
		_ = os.Remove(tmpPath)
		return err
	}
	defer os.Remove(tmpPath)

	_, err = runner.RunSudo(ctx, "install", "-m", "600", tmpPath, authPath)
	return err
}

func resolveHostOpencodeAuthPath() (string, error) {
	return resolveHostAuthPath(workDiskOpencodeAuthRelativePath)
}

func resolveHostClaudeAuthPath() (string, error) {
	return resolveHostAuthPath(workDiskClaudeAuthRelativePath)
}

func resolveHostPiAuthPath() (string, error) {
	return resolveHostAuthPath(workDiskPiAuthRelativePath)
}

func resolveHostAuthPath(relativePath string) (string, error) {
	home, err := os.UserHomeDir()
	if err != nil {
		return "", err
	}
	return filepath.Join(home, relativePath), nil
}

func resolveHostGlobalGitIdentity(ctx context.Context, runner system.CommandRunner) (gitIdentity, error) {
	name, err := gitConfigValue(ctx, runner, nil, "user.name")
	if err != nil {
		return gitIdentity{}, err
	}
	if name == "" {
		return gitIdentity{}, errors.New("host git user.name is empty")
	}

	email, err := gitConfigValue(ctx, runner, nil, "user.email")
	if err != nil {
		return gitIdentity{}, err
	}
	if email == "" {
		return gitIdentity{}, errors.New("host git user.email is empty")
	}

	return gitIdentity{Name: name, Email: email}, nil
}

func gitConfigValue(ctx context.Context, runner system.CommandRunner, extraArgs []string, key string) (string, error) {
	args := []string{"config"}
	args = append(args, extraArgs...)
	args = append(args, "--default", "", "--get", key)
	out, err := runner.Run(ctx, "git", args...)
	if err != nil {
		return "", err
	}
	return strings.TrimSpace(string(out)), nil
}

func writeGitIdentity(ctx context.Context, runner system.CommandRunner, gitConfigPath string, identity gitIdentity) error {
	existing, err := runner.RunSudo(ctx, "cat", gitConfigPath)
	if err != nil {
		existing = nil
	}

	tmpFile, err := os.CreateTemp("", "banger-gitconfig-*")
	if err != nil {
		return err
	}
	tmpPath := tmpFile.Name()
	if _, err := tmpFile.Write(existing); err != nil {
		_ = tmpFile.Close()
		_ = os.Remove(tmpPath)
		return err
	}
	if err := tmpFile.Close(); err != nil {
		_ = os.Remove(tmpPath)
		return err
	}
	defer os.Remove(tmpPath)

	if _, err := runner.Run(ctx, "git", "config", "--file", tmpPath, "user.name", identity.Name); err != nil {
		return err
	}
	if _, err := runner.Run(ctx, "git", "config", "--file", tmpPath, "user.email", identity.Email); err != nil {
		return err
	}
	_, err = runner.RunSudo(ctx, "install", "-m", "644", tmpPath, gitConfigPath)
	return err
}

func (d *Daemon) warnOpencodeAuthSyncSkipped(vm model.VMRecord, hostPath string, err error) {
	if d.logger == nil || err == nil {
		return
	}
	d.logger.Warn("guest opencode auth sync skipped", append(vmLogAttrs(vm), "host_path", hostPath, "error", err.Error())...)
}

func (d *Daemon) warnClaudeAuthSyncSkipped(vm model.VMRecord, hostPath string, err error) {
	if d.logger == nil || err == nil {
		return
	}
	d.logger.Warn("guest claude auth sync skipped", append(vmLogAttrs(vm), "host_path", hostPath, "error", err.Error())...)
}

func (d *Daemon) warnPiAuthSyncSkipped(vm model.VMRecord, hostPath string, err error) {
	if d.logger == nil || err == nil {
		return
	}
	d.logger.Warn("guest pi auth sync skipped", append(vmLogAttrs(vm), "host_path", hostPath, "error", err.Error())...)
}

func (d *Daemon) warnGitIdentitySyncSkipped(vm model.VMRecord, source string, err error) {
	if d.logger == nil || err == nil {
		return
	}
	d.logger.Warn("guest git identity sync skipped", append(vmLogAttrs(vm), "source", source, "error", err.Error())...)
}

func mergeAuthorizedKey(existing, managed []byte) []byte {
	managedLine := strings.TrimSpace(string(managed))
	if managedLine == "" {
		return append([]byte(nil), existing...)
	}

	lines := strings.Split(strings.ReplaceAll(string(existing), "\r\n", "\n"), "\n")
	out := make([]string, 0, len(lines)+1)
	found := false
	for _, line := range lines {
		line = strings.TrimRight(line, "\r")
		trimmed := strings.TrimSpace(line)
		if trimmed == "" {
			continue
		}
		if trimmed == managedLine {
			found = true
		}
		out = append(out, line)
	}
	if !found {
		out = append(out, managedLine)
	}
	return []byte(strings.Join(out, "\n") + "\n")
}