// Package agents defines the Agent runtime that ties core and shell together.
package agents

import (
	"context"
	"fmt"
	"io"
	"log/slog"
	"path/filepath"

	"maunium.net/go/mautrix/event"

	"github.com/enmanuel/agents/internal/config"
	"github.com/enmanuel/agents/pkg/decision"
	coretypes "github.com/enmanuel/agents/pkg/llm"
	"github.com/enmanuel/agents/pkg/personality"
	"github.com/enmanuel/agents/shell/effects"
	shelllm "github.com/enmanuel/agents/shell/llm"
	"github.com/enmanuel/agents/shell/matrix"
	"github.com/enmanuel/agents/shell/ssh"
)

// Agent is the assembled runtime: pure core + impure shell.
type Agent struct {
	cfg         *config.AgentConfig
	personality personality.Personality
	rules       []decision.Rule
	llm         coretypes.CompleteFunc
	matrix      *matrix.Client
	runner      *effects.Runner
	listener    *matrix.Listener
	logger      *slog.Logger
	cryptoStore io.Closer // non-nil when E2EE is enabled; closed on shutdown
}

// New assembles an Agent from its config, rules, and logger.
func New(cfg *config.AgentConfig, rules []decision.Rule, logger *slog.Logger) (*Agent, error) {
	// Matrix client
	matrixClient, err := matrix.New(cfg.Matrix)
	if err != nil {
		return nil, fmt.Errorf("matrix client: %w", err)
	}

	// E2EE — initialize before the sync loop starts
	var cryptoStore io.Closer
	if cfg.Matrix.Encryption.Enabled {
		storePath := filepath.Join(cfg.Matrix.Encryption.StorePath, "crypto.db")
		logger.Info("initializing e2ee", "store", storePath)
		cryptoStore, err = matrixClient.InitCrypto(context.Background(), storePath, cfg.Agent.ID)
		if err != nil {
			return nil, fmt.Errorf("e2ee init: %w", err)
		}
		logger.Info("e2ee ready")
	}

	// SSH executor
	sshExec := ssh.NewExecutor(cfg.SSH)

	// LLM client
	primaryLLM, err := shelllm.FromConfig(cfg.LLM.Primary)
	if err != nil {
		return nil, fmt.Errorf("primary LLM: %w", err)
	}

	var llmFunc coretypes.CompleteFunc = primaryLLM
	if cfg.LLM.Fallback.Provider != "" {
		fallbackLLM, err := shelllm.FromConfig(cfg.LLM.Fallback)
		if err != nil {
			logger.Warn("fallback LLM config error", "err", err)
		} else {
			llmFunc = shelllm.WithFallback(primaryLLM, fallbackLLM)
		}
	}

	// Effects runner
	runner := effects.NewRunner(matrixClient, sshExec, logger)

	a := &Agent{
		cfg:         cfg,
		rules:       rules,
		llm:         llmFunc,
		matrix:      matrixClient,
		runner:      runner,
		logger:      logger,
		cryptoStore: cryptoStore,
	}

	// Matrix event listener
	a.listener = matrix.NewListener(matrixClient, cfg.Matrix, a.handleEvent, logger)

	return a, nil
}

// Run starts the agent sync loop. Blocks until ctx is cancelled.
func (a *Agent) Run(ctx context.Context) error {
	if a.cryptoStore != nil {
		defer a.cryptoStore.Close()
	}
	a.logger.Info("agent starting", "id", a.cfg.Agent.ID, "name", a.cfg.Agent.Name)
	return a.listener.Run(ctx)
}

// handleEvent is called by the matrix Listener for each filtered incoming event.
func (a *Agent) handleEvent(ctx context.Context, msgCtx decision.MessageContext, evt *event.Event) {
	a.logger.Debug("handling event",
		"sender", msgCtx.SenderID,
		"is_dm", msgCtx.IsDirectMsg,
		"is_mention", msgCtx.IsMention,
		"command", msgCtx.Command,
	)

	if a.cfg.Personality.Behavior.TypingIndicator {
		_ = a.matrix.SendTyping(ctx, evt.RoomID.String(), true)
		defer a.matrix.SendTyping(ctx, evt.RoomID.String(), false)
	}

	actions := decision.Evaluate(msgCtx, a.rules)
	a.logger.Debug("rules evaluated", "matched_actions", len(actions))

	// If no rules matched and the message mentions the bot or is a DM, use LLM.
	if len(actions) == 0 && (msgCtx.IsMention || msgCtx.IsDirectMsg) {
		a.logger.Debug("no rules matched, falling back to LLM")
		actions = []decision.Action{{
			Kind: decision.ActionKindLLM,
			LLM:  &decision.LLMAction{ContextKey: msgCtx.RoomID},
		}}
	}

	if len(actions) == 0 {
		a.logger.Debug("no actions, ignoring message",
			"is_dm", msgCtx.IsDirectMsg,
			"is_mention", msgCtx.IsMention,
		)
		return
	}

	// Expand LLM actions inline (simplified — real impl would maintain conversation state)
	expanded := make([]decision.Action, 0, len(actions))
	for _, act := range actions {
		if act.Kind == decision.ActionKindLLM {
			reply, err := a.runLLM(ctx, msgCtx)
			if err != nil {
				a.logger.Error("llm error", "err", err)
				expanded = append(expanded, decision.Action{
					Kind:  decision.ActionKindReply,
					Reply: &decision.ReplyAction{Content: "Sorry, I encountered an error."},
				})
			} else {
				expanded = append(expanded, decision.Action{
					Kind:  decision.ActionKindReply,
					Reply: &decision.ReplyAction{Content: reply},
				})
			}
		} else {
			expanded = append(expanded, act)
		}
	}

	a.runner.Execute(ctx, evt.RoomID.String(), expanded)
}

func (a *Agent) runLLM(ctx context.Context, msgCtx decision.MessageContext) (string, error) {
	a.logger.Debug("calling LLM",
		"model", a.cfg.LLM.Primary.Model,
		"provider", a.cfg.LLM.Primary.Provider,
	)
	req := coretypes.CompletionRequest{
		Model:        a.cfg.LLM.Primary.Model,
		MaxTokens:    a.cfg.LLM.Primary.MaxTokens,
		Temperature:  a.cfg.LLM.Primary.Temperature,
		SystemPrompt: a.cfg.Agent.Description,
		Messages: []coretypes.Message{
			{Role: coretypes.RoleUser, Content: msgCtx.Content},
		},
	}
	resp, err := a.llm(ctx, req)
	if err != nil {
		a.logger.Error("LLM call failed", "model", req.Model, "err", err)
		return "", err
	}
	a.logger.Debug("LLM responded", "content_len", len(resp.Content))
	return resp.Content, nil
}