package main

import (
	"context"
	"log/slog"
	"os"
	"strings"
	"sync"
	"time"

	"github.com/enmanuel/agents/agents"
	"github.com/enmanuel/agents/internal/config"
	"github.com/enmanuel/agents/pkg/decision"
	"github.com/enmanuel/agents/pkg/orchestration"
	pksecurity "github.com/enmanuel/agents/pkg/security"
	"github.com/enmanuel/agents/shell/bus"
	agentlog "github.com/enmanuel/agents/shell/logger"
)

// runningAgent holds a live agent and the metadata needed to recreate it.
type runningAgent struct {
	agent      *agents.Agent
	cfg        *config.AgentConfig
	cfgPath    string
	logger     *slog.Logger
	logCleanup func()
}

// launchDeps holds shared resources needed to start/reload agents.
type launchDeps struct {
	agentBus   *bus.Bus
	orch       *orchHandle
	logDir     string
	logLevel   slog.Level
	parentCtx  context.Context
	secPolicy  pksecurity.SecurityPolicy // centralized security policy loaded from security/
}

// agentRegistry tracks all running agents by ID, enabling individual hot-reload.
type agentRegistry struct {
	mu     sync.Mutex
	agents map[string]*runningAgent
	deps   *launchDeps
}

func newAgentRegistry(deps *launchDeps) *agentRegistry {
	return &agentRegistry{
		agents: make(map[string]*runningAgent),
		deps:   deps,
	}
}

// register adds a running agent to the registry and starts its goroutine.
func (r *agentRegistry) register(ra *runningAgent) {
	r.mu.Lock()
	r.agents[ra.cfg.Agent.ID] = ra
	r.mu.Unlock()

	go func() {
		ra.logger.Info("agent running")
		if err := ra.agent.Run(r.deps.parentCtx); err != nil {
			ra.logger.Error("agent stopped with error", "err", err)
		}
	}()
}

// stopAndWait stops a running agent and waits for it to finish.
// Caller must NOT hold r.mu.
func (r *agentRegistry) stopAndWait(id string) {
	r.mu.Lock()
	ra, ok := r.agents[id]
	r.mu.Unlock()
	if !ok {
		return
	}

	ra.agent.Stop()
	select {
	case <-ra.agent.Done():
	case <-time.After(10 * time.Second):
		ra.logger.Warn("agent did not stop within 10s, forcing", "id", id)
	}

	// Unsubscribe from bus so no stale channel remains.
	r.deps.agentBus.Unsubscribe(bus.AgentID(id))
}

// reload stops an agent, re-reads its config, recreates it, and restarts it.
func (r *agentRegistry) reload(id string, rulesFor func(string, *slog.Logger) []decision.Rule) {
	r.mu.Lock()
	ra, ok := r.agents[id]
	r.mu.Unlock()
	if !ok {
		slog.Warn("reload: agent not found", "id", id)
		return
	}

	cfgPath := ra.cfgPath
	oldCleanup := ra.logCleanup

	ra.logger.Info("agent_reload_start", "id", id)

	// 1. Stop current instance and wait.
	r.stopAndWait(id)

	// 2. Cleanup old log writer.
	if oldCleanup != nil {
		oldCleanup()
	}

	// 3. Re-read config.
	cfg, err := config.Load(cfgPath)
	if err != nil {
		slog.Error("reload: failed to load config", "path", cfgPath, "err", err)
		return
	}
	if !cfg.Agent.Enabled {
		slog.Info("reload: agent is disabled, not restarting", "id", id)
		r.mu.Lock()
		delete(r.agents, id)
		r.mu.Unlock()
		return
	}

	// 4. New per-agent logger.
	newLogger, newCleanup, aErr := agentlog.NewAgentLogger(agentlog.LoggerConfig{
		BaseDir: r.deps.logDir,
		AgentID: cfg.Agent.ID,
		Level:   r.deps.logLevel,
	})
	if aErr != nil {
		newLogger = slog.Default().With("agent", cfg.Agent.ID)
		newCleanup = func() {}
	}

	// 5. Create new agent (validates config before discarding the old one).
	rules := rulesFor(cfg.Agent.ID, newLogger)
	agentACL := pksecurity.ResolveACL(cfg.Agent.ID, r.deps.secPolicy)
	newLogger.Debug("resolved acl for agent (reload)", "agent", cfg.Agent.ID, "acl_empty", agentACL.Empty())
	newAgent, err := agents.New(cfg, rules, agentACL, newLogger)
	if err != nil {
		newLogger.Error("reload: failed to create agent", "id", id, "err", err)
		newCleanup()
		return
	}

	// 6. Wire bus and orchestration.
	newAgent.SetBus(r.deps.agentBus)
	if r.deps.orch != nil {
		newAgent.SetInterceptor(r.deps.orch.orchestrator.Intercept)
		newAgent.SetMembershipNotify(r.deps.orch.orchestrator.NotifyMembership)
		r.deps.orch.orchestrator.RegisterParticipant(orchestration.ParticipantInfo{
			ID:           cfg.Agent.ID,
			MatrixUserID: cfg.Matrix.UserID,
			Description:  cfg.Agent.Description,
			Capabilities: cfg.Agent.Tags,
		})
	}

	newRA := &runningAgent{
		agent:      newAgent,
		cfg:        cfg,
		cfgPath:    cfgPath,
		logger:     newLogger,
		logCleanup: newCleanup,
	}

	r.mu.Lock()
	r.agents[id] = newRA
	r.mu.Unlock()

	// 7. Start new goroutine.
	go func() {
		newLogger.Info("agent running")
		if err := newAgent.Run(r.deps.parentCtx); err != nil {
			newLogger.Error("agent stopped with error", "err", err)
		}
	}()

	newLogger.Info("agent_reloaded", "id", id)
}

// reloadAll reloads every registered agent sequentially.
func (r *agentRegistry) reloadAll(rulesFor func(string, *slog.Logger) []decision.Rule) {
	r.mu.Lock()
	ids := make([]string, 0, len(r.agents))
	for id := range r.agents {
		ids = append(ids, id)
	}
	r.mu.Unlock()

	for _, id := range ids {
		r.reload(id, rulesFor)
	}
}

// waitAll blocks until all registered agents have stopped.
func (r *agentRegistry) waitAll() {
	r.mu.Lock()
	dones := make([]<-chan struct{}, 0, len(r.agents))
	for _, ra := range r.agents {
		dones = append(dones, ra.agent.Done())
	}
	r.mu.Unlock()

	for _, done := range dones {
		<-done
	}
}

// cleanupLogs calls every agent's log cleanup function (called on launcher shutdown).
func (r *agentRegistry) cleanupLogs() {
	r.mu.Lock()
	defer r.mu.Unlock()
	for _, ra := range r.agents {
		if ra.logCleanup != nil {
			ra.logCleanup()
		}
	}
}

// readReloadTarget reads the given file and returns the trimmed content.
// Returns "" if the file doesn't exist, is empty, or equals "*" (meaning reload all).
func readReloadTarget(path string) string {
	data, err := os.ReadFile(path)
	if err != nil {
		return ""
	}
	id := strings.TrimSpace(string(data))
	if id == "*" {
		return ""
	}
	return id
}