package process

import (
	"fmt"
	"os"
	"os/exec"
	"sync"

	"codespace/internal/util"
)

// Manager manages OpenCode processes per workspace.
type Manager interface {
	Start(workspaceID string, workspaceRoot string) error
	Stop(workspaceID string) error
	Restart(workspaceID string, workspaceRoot string) error
	Status(workspaceID string) Status
}

// LocalManager implements Manager using local OS processes.
type LocalManager struct {
	command  string
	args     []string
	mu       sync.Mutex
	sessions map[string]*Session
}

// NewManager creates a LocalManager with the given command.
// If command is empty, it defaults to "opencode".
func NewManager(command string) *LocalManager {
	return &LocalManager{
		command:  normalizeCommand(command),
		args:     []string{},
		sessions: make(map[string]*Session),
	}
}

// Start launches a process for the given workspace.
// Returns CodeConflict if a session is already running.
func (m *LocalManager) Start(workspaceID string, workspaceRoot string) error {
	m.mu.Lock()
	defer m.mu.Unlock()

	if sess, ok := m.sessions[workspaceID]; ok && sess.Cmd.Process != nil {
		if sess.Cmd.ProcessState == nil {
			return util.New(util.CodeConflict, "process already running")
		}
	}

	cmd := exec.Command(m.command, m.args...)
	cmd.Dir = workspaceRoot
	cmd.Env = append(os.Environ(), fmt.Sprintf("HOME=%s", workspaceRoot))

	if err := cmd.Start(); err != nil {
		return util.Wrap(util.CodeInternal, "failed to start process", err)
	}

	m.sessions[workspaceID] = &Session{
		WorkspaceID: workspaceID,
		Root:        workspaceRoot,
		Cmd:         cmd,
	}

	return nil
}

// Stop kills the process for the given workspace.
// Returns CodeNotFound if no session exists.
func (m *LocalManager) Stop(workspaceID string) error {
	m.mu.Lock()
	defer m.mu.Unlock()

	sess, ok := m.sessions[workspaceID]
	if !ok || sess.Cmd.Process == nil {
		return util.New(util.CodeNotFound, "no running process for workspace")
	}

	if err := sess.Cmd.Process.Kill(); err != nil {
		return util.Wrap(util.CodeInternal, "failed to stop process", err)
	}

	delete(m.sessions, workspaceID)
	return nil
}

// Restart stops (if running) then starts the process.
func (m *LocalManager) Restart(workspaceID string, workspaceRoot string) error {
	m.mu.Lock()
	if sess, ok := m.sessions[workspaceID]; ok && sess.Cmd.Process != nil {
		if sess.Cmd.ProcessState == nil {
			_ = sess.Cmd.Process.Kill()
			delete(m.sessions, workspaceID)
		}
	}
	m.mu.Unlock()

	return m.Start(workspaceID, workspaceRoot)
}

// Status returns the current process status for the workspace.
func (m *LocalManager) Status(workspaceID string) Status {
	m.mu.Lock()
	defer m.mu.Unlock()

	sess, ok := m.sessions[workspaceID]
	if !ok || sess.Cmd.Process == nil {
		return Status{WorkspaceID: workspaceID, Running: false}
	}

	if sess.Cmd.ProcessState != nil {
		return Status{WorkspaceID: workspaceID, Running: false}
	}

	return Status{
		WorkspaceID: workspaceID,
		Running:     true,
		PID:         sess.Cmd.Process.Pid,
	}
}