package opencode

import (
	"context"
	"fmt"
	"log/slog"
	"strings"
	"time"

	"banger/internal/vsockagent"
)

const (
	Port             = 4096
	Host             = "0.0.0.0"
	GuestBinaryPath  = "/usr/local/bin/opencode"
	ShimPath         = "/root/.local/share/mise/shims/opencode"
	ServiceName      = "banger-opencode.service"
	RunitServiceName = "banger-opencode"
	ReadyTimeout     = 45 * time.Second
	pollInterval     = 200 * time.Millisecond
)

func ServiceUnit() string {
	return fmt.Sprintf(`[Unit]
Description=Banger opencode server
After=network.target
RequiresMountsFor=/root

[Service]
Type=simple
Environment=HOME=/root
WorkingDirectory=/root
ExecStart=%s serve --hostname %s --port %d
Restart=on-failure
RestartSec=1

[Install]
WantedBy=multi-user.target
`, GuestBinaryPath, Host, Port)
}

func RunitRunScript() string {
	return fmt.Sprintf(`#!/bin/sh
set -e
export HOME=/root
cd /root
exec %s serve --hostname %s --port %d
`, GuestBinaryPath, Host, Port)
}

func Ready(listeners []vsockagent.PortListener) bool {
	for _, listener := range listeners {
		if strings.ToLower(strings.TrimSpace(listener.Proto)) != "tcp" {
			continue
		}
		if listener.Port == Port {
			return true
		}
	}
	return false
}

func WaitReady(ctx context.Context, logger *slog.Logger, socketPath string, report func(stage, detail string)) error {
	return waitReady(ctx, logger, socketPath, ReadyTimeout, report)
}

func waitReady(ctx context.Context, logger *slog.Logger, socketPath string, timeout time.Duration, report func(stage, detail string)) error {
	waitCtx, cancel := context.WithTimeout(ctx, timeout)
	defer cancel()

	ticker := time.NewTicker(pollInterval)
	defer ticker.Stop()

	var lastErr error
	for {
		portsCtx, portsCancel := context.WithTimeout(waitCtx, 3*time.Second)
		listeners, err := vsockagent.Ports(portsCtx, logger, socketPath)
		portsCancel()
		if err == nil {
			if Ready(listeners) {
				return nil
			}
			if report != nil {
				report("wait_opencode", fmt.Sprintf("waiting for opencode on guest port %d", Port))
			}
			lastErr = fmt.Errorf("guest port %d is not listening yet", Port)
		} else {
			if report != nil {
				report("wait_vsock_agent", "waiting for guest vsock agent")
			}
			lastErr = err
		}

		select {
		case <-waitCtx.Done():
			if lastErr != nil {
				return fmt.Errorf("opencode server did not become ready on guest port %d: %w", Port, lastErr)
			}
			return fmt.Errorf("opencode server did not become ready on guest port %d before timeout", Port)
		case <-ticker.C:
		}
	}
}