package sandbox

import (
	"bytes"
	"context"
	"fmt"
	"os"
	"os/exec"
	"path/filepath"
	"sync"
)

// HostSandbox runs tool calls directly on the host filesystem/shell — no
// container isolation, no new safety checks beyond what LocalRunner already
// did. It is safe for concurrent use; a mutex guards the working-directory
// field since GitClone/Cleanup mutate it.
//
// A HostSandbox with an empty working directory (the zero value, or one
// constructed via NewHostSandbox("")) represents "no sandbox configured" —
// matching LocalRunner's historical behavior for tasks without a
// project_dir: file/bash/glob tool calls fail with a "no sandbox working
// directory" error identical to the original dispatchAgentTool guard, and
// GitClone must be called (or the sandbox constructed with an existing dir)
// before those tools will work.
type HostSandbox struct {
	mu  sync.Mutex
	dir string
}

var _ Sandbox = (*HostSandbox)(nil)

// NewHostSandbox returns a HostSandbox rooted at dir. Pass "" to construct a
// not-yet-cloned sandbox (GitClone will establish the directory); pass an
// existing directory to reuse a prior sandbox (e.g. resuming a BLOCKED task)
// without cloning again.
func NewHostSandbox(dir string) *HostSandbox {
	return &HostSandbox{dir: dir}
}

// WorkDir returns the current working directory, or "" if none has been
// established yet.
func (s *HostSandbox) WorkDir() string {
	s.mu.Lock()
	defer s.mu.Unlock()
	return s.dir
}

// GitClone clones remote into a fresh temp directory (if this sandbox has no
// working directory yet) or into the existing one otherwise. branch, if
// non-empty, is passed as `git clone -b <branch>`; LocalRunner never set a
// branch, so passing "" reproduces its exact `git clone <remote> <dir>`
// invocation.
func (s *HostSandbox) GitClone(ctx context.Context, remote, branch string) error {
	s.mu.Lock()
	defer s.mu.Unlock()

	if s.dir == "" {
		tmpDir, err := os.MkdirTemp("", "claudomator-local-*")
		if err != nil {
			return fmt.Errorf("sandbox: create temp dir: %w", err)
		}
		s.dir = tmpDir
	}

	args := []string{"clone"}
	if branch != "" {
		args = append(args, "-b", branch)
	}
	args = append(args, remote, s.dir)
	cmd := exec.CommandContext(ctx, "git", args...)
	out, err := cmd.CombinedOutput()
	if err != nil {
		os.RemoveAll(s.dir)
		s.dir = ""
		return fmt.Errorf("sandbox: git clone: %w\n%s", err, out)
	}
	return nil
}

// GitPush pushes the working directory's current HEAD to origin. branch, if
// non-empty, is used as the push ref; "" reproduces LocalRunner's exact
// `git push origin HEAD` invocation.
func (s *HostSandbox) GitPush(ctx context.Context, branch string) error {
	s.mu.Lock()
	dir := s.dir
	s.mu.Unlock()
	if dir == "" {
		return fmt.Errorf("sandbox: git push: no sandbox working directory")
	}
	ref := branch
	if ref == "" {
		ref = "HEAD"
	}
	cmd := exec.CommandContext(ctx, "git", "-C", dir, "push", "origin", ref)
	out, err := cmd.CombinedOutput()
	if err != nil {
		return fmt.Errorf("sandbox: git push: %w\n%s", err, out)
	}
	return nil
}

// Cleanup removes the sandbox's working directory and resets it to "". A
// no-op if no working directory was ever established.
func (s *HostSandbox) Cleanup(_ context.Context) error {
	s.mu.Lock()
	defer s.mu.Unlock()
	if s.dir == "" {
		return nil
	}
	err := os.RemoveAll(s.dir)
	s.dir = ""
	return err
}

// resolvePath joins a relative path against the working directory, leaving
// absolute paths untouched — matching dispatchAgentTool's historical
// behavior exactly.
func (s *HostSandbox) resolvePath(p string) (string, error) {
	s.mu.Lock()
	dir := s.dir
	s.mu.Unlock()
	if dir == "" {
		return "", fmt.Errorf("no sandbox working directory")
	}
	if !filepath.IsAbs(p) {
		p = filepath.Join(dir, p)
	}
	return p, nil
}

func (s *HostSandbox) ReadFile(_ context.Context, path string) (string, error) {
	p, err := s.resolvePath(path)
	if err != nil {
		return "", fmt.Errorf("read_file: %w", err)
	}
	data, err := os.ReadFile(p)
	if err != nil {
		return "", err
	}
	return string(data), nil
}

func (s *HostSandbox) WriteFile(_ context.Context, path, content string) error {
	p, err := s.resolvePath(path)
	if err != nil {
		return fmt.Errorf("write_file: %w", err)
	}
	if err := os.MkdirAll(filepath.Dir(p), 0o755); err != nil {
		return err
	}
	return os.WriteFile(p, []byte(content), 0o644)
}

// maxToolOutput caps stdout/stderr returned from RunBash, matching
// dispatchAgentTool's historical 8KB truncation.
const maxToolOutput = 8 * 1024

func (s *HostSandbox) RunBash(ctx context.Context, command string) (stdout, stderr string, exitCode int, err error) {
	s.mu.Lock()
	dir := s.dir
	s.mu.Unlock()
	if dir == "" {
		return "", "", 0, fmt.Errorf("run_bash: no sandbox working directory")
	}

	cmd := exec.CommandContext(ctx, "sh", "-c", command)
	cmd.Dir = dir
	var outBuf, errBuf bytes.Buffer
	cmd.Stdout = &outBuf
	cmd.Stderr = &errBuf
	runErr := cmd.Run()
	if runErr != nil {
		if exitErr, ok := runErr.(*exec.ExitError); ok {
			exitCode = exitErr.ExitCode()
		} else {
			return "", "", 0, runErr
		}
	}

	stdout = outBuf.String()
	stderr = errBuf.String()
	if len(stdout) > maxToolOutput {
		stdout = stdout[:maxToolOutput] + "\n[truncated]"
	}
	if len(stderr) > maxToolOutput {
		stderr = stderr[:maxToolOutput] + "\n[truncated]"
	}
	return stdout, stderr, exitCode, nil
}

func (s *HostSandbox) Glob(_ context.Context, pattern string) ([]string, error) {
	s.mu.Lock()
	dir := s.dir
	s.mu.Unlock()
	if dir == "" {
		return nil, fmt.Errorf("glob: no sandbox working directory")
	}
	if !filepath.IsAbs(pattern) {
		pattern = filepath.Join(dir, pattern)
	}
	matches, err := filepath.Glob(pattern)
	if err != nil {
		return nil, err
	}
	rel := make([]string, 0, len(matches))
	for _, m := range matches {
		r, relErr := filepath.Rel(dir, m)
		if relErr != nil {
			r = m
		}
		rel = append(rel, r)
	}
	return rel, nil
}