// workflow — local runner for the Workflow Engine
//
// Usage:
//
//	workflow server [--port 8080] [--config .env]
//	workflow run -workflow FILE -workspace-id ID [-params JSON] [-mode MODE] [-v]
//	workflow help
//
// Config (.env in working directory, or --config flag):
//
//	LLM_URL=http://localhost:4000
//	LLM_KEY=sk-xxx
//	LLM_MODEL=gpt-4o
//	WORKSPACE_ROOT=./workspace
//	PORT=8080
package main

import (
	"context"
	"encoding/json"
	"flag"
	"fmt"
	"log"
	"net/http"
	"os"
	"strings"
	"time"

	"workflow"
	"workflow/config"
)

func main() {
	if len(os.Args) < 2 {
		printHelp()
		os.Exit(1)
	}

	switch os.Args[1] {
	case "server":
		cmdServer(os.Args[2:])
	case "run":
		cmdRun(os.Args[2:])
	case "help", "--help", "-h":
		printHelp()
	default:
		fmt.Fprintf(os.Stderr, "unknown command: %q\n\n", os.Args[1])
		printHelp()
		os.Exit(1)
	}
}

func printHelp() {
	fmt.Print(`workflow — Workflow Engine local runner

Commands:
  server   Start local HTTP server (POST /run → SSE event stream)
  run      Execute a workflow file directly in the terminal
  help     Show this help

Server usage:
  workflow server [--port 8080] [--config .env]

Run usage:
  workflow run -workflow FILE -workspace-id ID [options]
    -workflow      Workflow JSON file (required)
    -workspace-id  Project identifier / gid (required)
    -params        Input params as JSON: '{"userRequest":"..."}'
    -mode          create | patch | regenerate | validate  (default: create)
    -config        Config file path (default: .env in CWD)
    -v             Verbose: print all events

Config file (.env or --config path):
  LLM_URL=http://localhost:4000
  LLM_KEY=sk-xxx
  LLM_MODEL=gpt-4o
  WORKSPACE_ROOT=./workspace
  PORT=8080

`)
}

// ─────────────────────────────────────────────────────────────────────────────
// server subcommand
// ─────────────────────────────────────────────────────────────────────────────

func cmdServer(args []string) {
	fs := flag.NewFlagSet("server", flag.ExitOnError)
	cfgFile := fs.String("config", "", "Config file (default: .env in CWD)")
	fs.Usage = func() {
		fmt.Fprintln(os.Stderr, "Usage: workflow server [--config FILE]")
		fs.PrintDefaults()
	}
	fs.Parse(args)

	cfg := config.Load(*cfgFile)

	log.SetFlags(log.Ltime | log.Lmsgprefix)
	log.SetPrefix("workflow ")
	log.Printf("endpoint  : POST http://localhost:%s/run", cfg.Server.Port)
	log.Printf("workspace : %s/<workspaceId>/", cfg.Workspace.Root)
	log.Printf("llm url   : %s", cfg.LLM.URL)
	log.Printf("llm model : %s", cfg.LLM.Model)
	log.Printf("llm key   : %s", config.MaskKey(cfg.LLM.Key))

	mux := http.NewServeMux()
	mux.HandleFunc("/run", serverRunHandler(cfg))
	mux.HandleFunc("/health", func(w http.ResponseWriter, _ *http.Request) {
		w.Header().Set("Content-Type", "application/json")
		fmt.Fprintf(w, `{"status":"ok","ts":%q}`+"\n", nowTS())
	})

	srv := &http.Server{
		Addr:        ":" + cfg.Server.Port,
		Handler:     mux,
		ReadTimeout: 30 * time.Second,
		IdleTimeout: 120 * time.Second,
		// WriteTimeout intentionally 0 — SSE streams can be long
	}
	log.Printf("Listening on :%s", cfg.Server.Port)
	if err := srv.ListenAndServe(); err != nil {
		log.Fatal(err)
	}
}

// RunRequest is the JSON body for POST /run.
type RunRequest struct {
	WorkflowID   string                 `json:"workflowId"`
	WorkflowDef  map[string]interface{} `json:"workflowDef"`
	WorkflowFile string                 `json:"workflowFile"`
	RunParams    workflow.RunParams     `json:"runParams"`
}

// sseEvent mirrors the spec §13.2 event shape.
type sseEvent struct {
	RunID   string                 `json:"run_id"`
	Seq     int                    `json:"seq"`
	TS      string                 `json:"ts"`
	Type    string                 `json:"type"`
	StepID  *string                `json:"step_id"`
	Payload map[string]interface{} `json:"payload"`
}

func writeSSE(w http.ResponseWriter, f http.Flusher, ev sseEvent) {
	data, _ := json.Marshal(ev)
	fmt.Fprintf(w, "data: %s\n\n", data)
	f.Flush()
}

func serverRunHandler(cfg config.Config) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		if r.Method != http.MethodPost {
			http.Error(w, "POST /run only", http.StatusMethodNotAllowed)
			return
		}

		var req RunRequest
		if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
			http.Error(w, "invalid JSON: "+err.Error(), http.StatusBadRequest)
			return
		}

		wf, err := loadWorkflow(req)
		if err != nil {
			http.Error(w, err.Error(), http.StatusBadRequest)
			return
		}

		eng, err := workflow.NewEngine(wf)
		if err != nil {
			http.Error(w, "engine: "+err.Error(), http.StatusBadRequest)
			return
		}

		adapters, err := buildAdapters(cfg, req.RunParams.WorkspaceID)
		if err != nil {
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}

		w.Header().Set("Content-Type", "text/event-stream")
		w.Header().Set("Cache-Control", "no-cache")
		w.Header().Set("Connection", "keep-alive")
		w.Header().Set("X-Accel-Buffering", "no")

		flusher, ok := w.(http.Flusher)
		if !ok {
			http.Error(w, "streaming unsupported", http.StatusInternalServerError)
			return
		}

		runID := fmt.Sprintf("run_%d", time.Now().UnixMilli())
		label := req.WorkflowID
		if label == "" {
			label = wf.Name
		}
		log.Printf("[%s] start workflow=%s gid=%s mode=%s",
			runID, label, req.RunParams.WorkspaceID, req.RunParams.Mode)

		result, err := eng.ExecuteWithRunParams(r.Context(), nil, adapters, req.RunParams)
		if err != nil {
			writeSSE(w, flusher, sseEvent{
				RunID: runID, Seq: 1, TS: nowTS(), Type: "workflow_failed",
				Payload: map[string]interface{}{"error": err.Error()},
			})
			return
		}

		seq := 1
		for ev := range result.RunEventStream {
			payload := ev.Payload
			if payload == nil {
				payload = map[string]interface{}{}
			}
			writeSSE(w, flusher, sseEvent{
				RunID: runID, Seq: seq, TS: nowTS(),
				Type: string(ev.Type), StepID: ev.StepID, Payload: payload,
			})
			seq++
		}
		log.Printf("[%s] done status=%s events=%d", runID, result.Context.Status, seq-1)
	}
}

// ─────────────────────────────────────────────────────────────────────────────
// run subcommand
// ─────────────────────────────────────────────────────────────────────────────

func cmdRun(args []string) {
	fs := flag.NewFlagSet("run", flag.ExitOnError)
	workflowFile  := fs.String("workflow",      "", "Workflow JSON file (required)")
	workspaceID   := fs.String("workspace-id",  envOr("WORKSPACE_ID", ""), "Project identifier / gid (required)")
	workspaceRoot := fs.String("workspace-root", "", "Override WORKSPACE_ROOT from config")
	paramsJSON    := fs.String("params",         "", `Input params JSON: '{"key":"value"}'`)
	mode          := fs.String("mode",           "create", "create|patch|regenerate|validate")
	cfgFile       := fs.String("config",         "", "Config file (default: .env in CWD)")
	verbose       := fs.Bool("v",               false, "Verbose: print all events")
	fs.Usage = func() {
		fmt.Fprintln(os.Stderr, "Usage: workflow run -workflow FILE -workspace-id ID [options]")
		fs.PrintDefaults()
	}
	fs.Parse(args)

	if *workflowFile == "" || *workspaceID == "" {
		fs.Usage()
		os.Exit(1)
	}

	cfg := config.Load(*cfgFile)
	if *workspaceRoot != "" {
		cfg.Workspace.Root = *workspaceRoot
	}

	wfBytes, err := os.ReadFile(*workflowFile)
	if err != nil {
		fatalf("read workflow: %v", err)
	}
	var wf workflow.Workflow
	if err := json.Unmarshal(wfBytes, &wf); err != nil {
		fatalf("parse workflow: %v", err)
	}

	var params map[string]interface{}
	if strings.TrimSpace(*paramsJSON) != "" {
		if err := json.Unmarshal([]byte(*paramsJSON), &params); err != nil {
			fatalf("parse -params: %v", err)
		}
	}

	fmt.Printf("▶  workflow    : %s (v%s)\n", wf.Name, wf.Version)
	fmt.Printf("   workspace-id: %s\n", *workspaceID)
	fmt.Printf("   workspace   : %s/%s\n", cfg.Workspace.Root, *workspaceID)
	fmt.Printf("   mode        : %s\n", *mode)
	if len(params) > 0 {
		raw, _ := json.Marshal(params)
		fmt.Printf("   params      : %s\n", raw)
	}
	fmt.Printf("   llm         : %s  model=%s\n\n", cfg.LLM.URL, cfg.LLM.Model)

	adapters, err := buildAdapters(cfg, *workspaceID)
	if err != nil {
		fatalf("adapters: %v", err)
	}

	eng, err := workflow.NewEngine(&wf)
	if err != nil {
		fatalf("engine: %v", err)
	}

	start := time.Now()
	result, err := eng.ExecuteWithRunParams(context.Background(), nil, adapters,
		workflow.RunParams{Params: params, WorkspaceID: *workspaceID, Mode: *mode})
	if err != nil {
		fatalf("execute: %v", err)
	}

	var steps, llms int
	for ev := range result.RunEventStream {
		switch ev.Type {
		case workflow.RunEventStepStart:
			if ev.StepID != nil {
				fmt.Printf("  → %-30s\n", *ev.StepID)
			}
		case workflow.RunEventStepDone:
			steps++
		case workflow.RunEventStepSkipped:
			if ev.StepID != nil {
				fmt.Printf("  ↷ %-30s (skipped)\n", *ev.StepID)
			}
		case workflow.RunEventStepError:
			id := ""
			if ev.StepID != nil {
				id = *ev.StepID
			}
			fmt.Printf("  ✗ %-30s ERROR: %v\n", id, ev.Payload["error"])
		case workflow.RunEventLLMDone:
			llms++
			id := ""
			if ev.StepID != nil {
				id = *ev.StepID
			}
			fmt.Printf("     llm_done  %s  %vms  model=%v\n",
				id, ev.Payload["latency_ms"], ev.Payload["model"])
			if u, ok := ev.Payload["usage"].(map[string]interface{}); ok {
				fmt.Printf("     tokens    in=%v out=%v total=%v\n",
					u["input_tokens"], u["output_tokens"], u["total_tokens"])
			}
		default:
			if *verbose {
				raw, _ := json.Marshal(ev.Payload)
				id := ""
				if ev.StepID != nil {
					id = *ev.StepID
				}
				fmt.Printf("  ~ %-20s %-25s %s\n", ev.Type, id, raw)
			}
		}
	}

	fmt.Printf("\n━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━\n")
	status := result.Context.Status
	icon := "✓"
	if status == workflow.StatusFailed {
		icon = "✗"
	}
	fmt.Printf("%s  %s   steps=%d  llm=%d  %v\n",
		icon, status, steps, llms, time.Since(start).Round(time.Millisecond))

	if len(result.Context.Variables) > 0 {
		fmt.Println("\n── variables ──")
		for k, v := range result.Context.Variables {
			if s, ok := v.(string); ok {
				if len(s) > 120 {
					fmt.Printf("  %-20s = %q…\n", k, s[:120])
				} else {
					fmt.Printf("  %-20s = %q\n", k, s)
				}
			} else {
				raw, _ := json.MarshalIndent(v, "  ", "  ")
				fmt.Printf("  %-20s = %s\n", k, raw)
			}
		}
	}
	if len(result.Context.Artifacts) > 0 {
		fmt.Println("\n── artifacts ──")
		for p := range result.Context.Artifacts {
			fmt.Printf("  %s/%s%s\n", cfg.Workspace.Root, *workspaceID, p)
		}
	}
	fmt.Println()

	if status == workflow.StatusFailed {
		os.Exit(1)
	}
}

// ─────────────────────────────────────────────────────────────────────────────
// shared helpers
// ─────────────────────────────────────────────────────────────────────────────

func loadWorkflow(req RunRequest) (*workflow.Workflow, error) {
	var wf workflow.Workflow
	switch {
	case req.WorkflowFile != "":
		data, err := os.ReadFile(req.WorkflowFile)
		if err != nil {
			return nil, fmt.Errorf("read workflowFile: %w", err)
		}
		if err := json.Unmarshal(data, &wf); err != nil {
			return nil, fmt.Errorf("parse workflowFile: %w", err)
		}
	case req.WorkflowDef != nil:
		raw, _ := json.Marshal(req.WorkflowDef)
		if err := json.Unmarshal(raw, &wf); err != nil {
			return nil, fmt.Errorf("parse workflowDef: %w", err)
		}
	default:
		return nil, fmt.Errorf("provide workflowDef or workflowFile")
	}
	return &wf, nil
}

func buildAdapters(cfg config.Config, workspaceID string) (*workflow.Adapters, error) {
	gid := workspaceID
	if gid == "" {
		gid = "default"
	}

	// v3.16+: Build multi-provider LLM adapter registry
	registry := buildLLMRegistry(cfg)

	file, err := workflow.NewLocalFileAdapter(cfg.Workspace.Root, gid)
	if err != nil {
		return nil, fmt.Errorf("file adapter: %w", err)
	}
	return &workflow.Adapters{
		Service:            workflow.NewDefaultServiceAdapter(),
		Component:          workflow.NewDefaultComponentAdapter(),
		LLM:                registry, // LLMAdapterRegistry implements LLMAdapter
		LLMAdapterRegistry: registry,
		File:               file,
	}, nil
}

// buildLLMRegistry creates a multi-provider LLM adapter registry (v3.16+).
// It reads cfg.LLM (global default) and cfg.Providers (per-provider) to build
// adapters for each known provider (openai, anthropic), then determines
// the default adapter from LLM_MODEL or LLM_URL.
func buildLLMRegistry(cfg config.Config) *workflow.LLMAdapterRegistry {
	// Determine default provider from LLM_MODEL (provider/modelId format) or LLM_URL
	defaultProvider := "openai"
	defaultModelId := cfg.LLM.Model
	if strings.Contains(cfg.LLM.Model, "/") {
		parts := strings.SplitN(cfg.LLM.Model, "/", 2)
		defaultProvider = parts[0]
		defaultModelId = parts[1]
	} else if strings.Contains(cfg.LLM.URL, "anthropic.com") {
		defaultProvider = "anthropic"
	}

	// Build OpenAI adapter
	openaiKey := cfg.LLM.Key // fallback
	openaiModel := defaultModelId
	openaiURL := cfg.LLM.URL
	if p, ok := cfg.Providers["openai"]; ok {
		if p.APIKey != "" {
			openaiKey = p.APIKey
		}
		if p.Model != "" {
			openaiModel = p.Model
		}
		if p.BaseURL != "" {
			openaiURL = p.BaseURL
		}
	}
	// Only use openaiModel as default if openai IS the default provider
	if defaultProvider != "openai" {
		if p, ok := cfg.Providers["openai"]; ok && p.Model != "" {
			openaiModel = p.Model
		} else {
			openaiModel = "" // no default model for non-default provider
		}
	}
	openaiAdapter := workflow.NewOpenAIAdapter(workflow.OpenAIConfig{
		BaseURL: openaiURL,
		APIKey:  openaiKey,
		Model:   openaiModel,
	})

	// Build Anthropic adapter
	anthropicKey := cfg.LLM.Key // fallback
	anthropicModel := ""
	anthropicURL := "https://api.anthropic.com"
	if p, ok := cfg.Providers["anthropic"]; ok {
		if p.APIKey != "" {
			anthropicKey = p.APIKey
		}
		if p.Model != "" {
			anthropicModel = p.Model
		}
		if p.BaseURL != "" {
			anthropicURL = p.BaseURL
		}
	}
	// Use defaultModelId if anthropic is the default provider and no provider-specific model
	if defaultProvider == "anthropic" && anthropicModel == "" {
		anthropicModel = defaultModelId
	}
	anthropicAdapter := workflow.NewAnthropicAdapter(workflow.AnthropicConfig{
		APIKey:  anthropicKey,
		Model:   anthropicModel,
		BaseURL: anthropicURL,
	})

	// Select default adapter based on determined provider
	var defaultAdapter workflow.LLMAdapter
	switch defaultProvider {
	case "anthropic":
		defaultAdapter = anthropicAdapter
	default:
		defaultAdapter = openaiAdapter
	}

	registry := workflow.NewLLMAdapterRegistry(defaultAdapter, defaultProvider)
	registry.Register("openai", openaiAdapter)
	registry.Register("anthropic", anthropicAdapter)

	return registry
}

func nowTS() string {
	return time.Now().UTC().Format("2006-01-02T15:04:05.000Z")
}

func envOr(key, fallback string) string {
	if v := os.Getenv(key); v != "" {
		return v
	}
	return fallback
}

func fatalf(format string, args ...interface{}) {
	fmt.Fprintf(os.Stderr, "error: "+format+"\n", args...)
	os.Exit(1)
}