package tui

import (
	"context"
	"fmt"
	"os"
	"os/exec"
	"strings"
	"time"

	tea "charm.land/bubbletea/v2"

	"superwork-tui/internal/issue"
)

// Phase identifies which tmux window is being managed.
type Phase string

const (
	PhaseBrain  Phase = "brain"
	PhaseImpl   Phase = "impl"
	PhaseReview Phase = "review"
	PhaseTest   Phase = "test"
)

// windowName returns the tmux window name for a given issue and phase.
func windowName(issueNumber int, phase Phase) string {
	return fmt.Sprintf("%d-%s", issueNumber, phase)
}

// resolveSessionName returns the current tmux session name when running inside
// tmux, or "superwork" otherwise.
func resolveSessionName() string {
	if os.Getenv("TMUX") == "" {
		return "superwork"
	}
	out, err := exec.Command("tmux", "display-message", "-p", "#S").Output()
	if err != nil {
		return "superwork"
	}
	name := strings.TrimRight(string(out), "\n")
	if name == "" {
		return "superwork"
	}
	return name
}

// TmuxRunner is a function that executes a tmux subcommand and returns its output.
// It is injectable for tests.
type TmuxRunner func(args ...string) ([]byte, error)

// SessionManager orchestrates tmux sessions for superwork issues.
// It owns its own TmuxRunner so tests can inject a recorder without touching
// the tmux package's global runner.
type SessionManager struct {
	run TmuxRunner
}

// NewSessionManager returns a SessionManager backed by the given runner.
func NewSessionManager(runner TmuxRunner) *SessionManager {
	return &SessionManager{run: runner}
}

// defaultTmuxRunner is the production runner used when no test runner is injected.
func defaultTmuxRunner(args ...string) ([]byte, error) {
	out, err := exec.Command("tmux", args...).CombinedOutput()
	if err != nil {
		return nil, fmt.Errorf("tmux %s: %w\n%s", args[0], err, out)
	}
	return out, nil
}

// ensureSession creates the named session if it does not already exist.
func (s *SessionManager) ensureSession(name string) error {
	_, err := s.run("has-session", "-t", "="+name)
	if err == nil {
		return nil // already exists
	}
	_, err = s.run("new-session", "-d", "-s", name)
	return err
}

// windowExists reports whether the given window name exists in the session.
func (s *SessionManager) windowExists(session, window string) (bool, error) {
	out, err := s.run("list-windows", "-t", session, "-F", "#{window_name}")
	if err != nil {
		return false, err
	}
	raw := strings.TrimRight(string(out), "\n")
	if raw == "" {
		return false, nil
	}
	for _, w := range strings.Split(raw, "\n") {
		if w == window {
			return true, nil
		}
	}
	return false, nil
}

// OpenOrFocus ensures the session exists, then focuses the window for the given
// phase+issue — creating it (with cwd and command) if it does not yet exist.
func (s *SessionManager) OpenOrFocus(_ context.Context, phase Phase, iss issue.Issue, cwd, command string) error {
	session := resolveSessionName()
	win := windowName(iss.Number, phase)

	if err := s.ensureSession(session); err != nil {
		return fmt.Errorf("ensure session: %w", err)
	}

	exists, err := s.windowExists(session, win)
	if err != nil {
		return fmt.Errorf("check window: %w", err)
	}

	if !exists {
		args := []string{"new-window", "-t", session + ":", "-n", win, "-c", cwd}
		if command != "" {
			args = append(args, command)
		}
		if _, err := s.run(args...); err != nil {
			return fmt.Errorf("new window: %w", err)
		}
	}

	if _, err := s.run("select-window", "-t", session+":"+win); err != nil {
		return fmt.Errorf("select window: %w", err)
	}
	return nil
}

// Inject sends text (followed by Enter) to the issue's phase window.
func (s *SessionManager) Inject(_ context.Context, phase Phase, iss issue.Issue, text string) error {
	session := resolveSessionName()
	win := windowName(iss.Number, phase)
	if _, err := s.run("send-keys", "-t", session+":"+win, "-l", "--", text); err != nil {
		return fmt.Errorf("send-keys literal: %w", err)
	}
	if _, err := s.run("send-keys", "-t", session+":"+win, "Enter"); err != nil {
		return fmt.Errorf("send-keys enter: %w", err)
	}
	return nil
}

// Close kills the tmux window for the given issue and phase.
func (s *SessionManager) Close(_ context.Context, phase Phase, iss issue.Issue, session string) error {
	win := windowName(iss.Number, phase)
	if _, err := s.run("kill-window", "-t", session+":"+win); err != nil {
		return fmt.Errorf("kill window: %w", err)
	}
	return nil
}

// claudeCmdOpts configures the claudeCmd builder.
type claudeCmdOpts struct {
	ResumeSessionID     string
	ProfilePath         string
	Prompt              string
	EffortHigh          bool
	SystemPromptCommand string
}

// claudeCmd builds a claude CLI command string from opts.
// Flag order matches TypeScript: [--effort high] --dangerously-skip-permissions
// [--settings <profile>] [--system-prompt="$(cmd)"] (--resume <id> | <prompt>)
func claudeCmd(opts claudeCmdOpts) string {
	parts := []string{"claude"}
	if opts.EffortHigh {
		parts = append(parts, "--effort", "high")
	}
	parts = append(parts, "--dangerously-skip-permissions")
	if opts.ProfilePath != "" {
		parts = append(parts, "--settings", shellQuote(opts.ProfilePath))
	}
	if opts.SystemPromptCommand != "" {
		parts = append(parts, `--system-prompt="$(`+opts.SystemPromptCommand+`)"`)
	}
	if opts.ResumeSessionID != "" {
		parts = append(parts, "--resume", shellQuote(opts.ResumeSessionID))
	} else if opts.Prompt != "" {
		parts = append(parts, shellQuote(opts.Prompt))
	}
	return strings.Join(parts, " ")
}

// claudeResumeCmd returns the CLI command to resume a Claude brainstorm session.
func claudeResumeCmd(sessionID, profilePath, systemPromptCommand string) string {
	return claudeCmd(claudeCmdOpts{
		ResumeSessionID:     sessionID,
		ProfilePath:         profilePath,
		SystemPromptCommand: systemPromptCommand,
	})
}

// shellQuote wraps s in single quotes (escaping any embedded single quote) so a
// path containing spaces or special characters survives the shell that tmux runs
// the window command through.
func shellQuote(s string) string {
	return "'" + strings.ReplaceAll(s, "'", `'\''`) + "'"
}

// tabAliveMsg carries the window list from a periodic tmux poll.
type tabAliveMsg struct {
	windows []string
}

// tabAliveCmd returns a tea.Cmd that polls tmux every ~2s for live windows.
func tabAliveCmd(sessionName string) tea.Cmd {
	return tea.Tick(2*time.Second, func(_ time.Time) tea.Msg {
		mgr := NewSessionManager(defaultTmuxRunner)
		wins, _ := mgr.listWindows(sessionName)
		return tabAliveMsg{windows: wins}
	})
}

// listWindows returns window names for the given session.
func (s *SessionManager) listWindows(session string) ([]string, error) {
	out, err := s.run("list-windows", "-t", session, "-F", "#{window_name}")
	if err != nil {
		return nil, err
	}
	raw := strings.TrimRight(string(out), "\n")
	if raw == "" {
		return nil, nil
	}
	return strings.Split(raw, "\n"), nil
}

// RunInWindow opens a named tmux window (or focuses it if it exists) and runs command in it.
func (s *SessionManager) RunInWindow(ctx context.Context, winName, cwd, command string) error {
	session := resolveSessionName()
	if err := s.ensureSession(session); err != nil {
		return fmt.Errorf("ensure session: %w", err)
	}
	exists, err := s.windowExists(session, winName)
	if err != nil {
		return fmt.Errorf("check window: %w", err)
	}
	if exists {
		if _, err := s.run("select-window", "-t", session+":"+winName); err != nil {
			return fmt.Errorf("select window: %w", err)
		}
		return nil
	}
	args := []string{"new-window", "-t", session + ":", "-n", winName, "-c", cwd}
	if command != "" {
		args = append(args, command)
	}
	if _, err := s.run(args...); err != nil {
		return fmt.Errorf("new window: %w", err)
	}
	if _, err := s.run("select-window", "-t", session+":"+winName); err != nil {
		return fmt.Errorf("select window: %w", err)
	}
	return nil
}

// reconcileTabs sets the *TabOpen fields on each issue based on which tmux
// windows are currently alive.
func reconcileTabs(issues []issue.Issue, aliveWindows []string) []issue.Issue {
	alive := make(map[string]bool, len(aliveWindows))
	for _, w := range aliveWindows {
		alive[w] = true
	}
	out := make([]issue.Issue, len(issues))
	for i, iss := range issues {
		iss.BrainstormTabOpen = alive[windowName(iss.Number, PhaseBrain)]
		iss.ImplementTabOpen = alive[windowName(iss.Number, PhaseImpl)]
		iss.ReviewTabOpen = alive[windowName(iss.Number, PhaseReview)]
		iss.TestTabOpen = alive[windowName(iss.Number, PhaseTest)]
		out[i] = iss
	}
	return out
}

// sessionActionResultMsg carries the result of an async tmux operation.
type sessionActionResultMsg struct {
	err error
}