package main

import (
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"io"
	"log/slog"
	"net/http"
	"os"
	"time"

	"github.com/nats-io/nats.go"

	"git.daviestechlabs.io/daviestechlabs/handler-base/config"
	"git.daviestechlabs.io/daviestechlabs/handler-base/handler"
	"git.daviestechlabs.io/daviestechlabs/handler-base/messages"
	"git.daviestechlabs.io/daviestechlabs/handler-base/natsutil"
	"google.golang.org/protobuf/proto"
)

// Pipeline definitions — maps pipeline name to engine config.
var pipelines = map[string]pipelineDef{
	"document-ingestion": {Engine: "argo", Template: "document-ingestion"},
	"batch-inference":    {Engine: "argo", Template: "batch-inference"},
	"rag-query":          {Engine: "kubeflow", PipelineID: "rag-pipeline"},
	"voice-pipeline":     {Engine: "kubeflow", PipelineID: "voice-pipeline"},
	"model-evaluation":   {Engine: "argo", Template: "model-evaluation"},
}

type pipelineDef struct {
	Engine     string // "argo" or "kubeflow"
	Template   string // Argo WorkflowTemplate name
	PipelineID string // Kubeflow pipeline ID
}

func main() {
	cfg := config.Load()
	cfg.ServiceName = "pipeline-bridge"
	cfg.NATSQueueGroup = "pipeline-bridges"

	kubeflowHost := getEnv("KUBEFLOW_HOST", "http://ml-pipeline.kubeflow.svc.cluster.local:8888")
	argoHost := getEnv("ARGO_HOST", "http://argo-server.argo.svc.cluster.local:2746")
	argoNamespace := getEnv("ARGO_NAMESPACE", "ai-ml")

	httpClient := &http.Client{Timeout: 60 * time.Second}

	h := handler.New("ai.pipeline.trigger", cfg)

	h.OnTypedMessage(func(ctx context.Context, msg *nats.Msg) (proto.Message, error) {
		var req messages.PipelineTrigger
		if err := natsutil.Decode(msg.Data, &req); err != nil {
			return &messages.PipelineStatus{Status: "error", Error: "Invalid request encoding"}, nil
		}

		requestID := req.RequestId
		if requestID == "" {
			requestID = "unknown"
		}
		pipelineName := req.Pipeline
		params := req.Parameters
		if params == nil {
			params = map[string]string{}
		}

		slog.Info("triggering pipeline", "pipeline", pipelineName, "request_id", requestID)

		// Validate pipeline
		pipeline, ok := pipelines[pipelineName]
		if !ok {
			names := make([]string, 0, len(pipelines))
			for k := range pipelines {
				names = append(names, k)
			}
			return &messages.PipelineStatus{
				RequestId:          requestID,
				Status:             "error",
				Error:              fmt.Sprintf("Unknown pipeline: %s", pipelineName),
				AvailablePipelines: names,
			}, nil
		}

		var runID string
		var err error

		if pipeline.Engine == "argo" {
			runID, err = submitArgo(ctx, httpClient, argoHost, argoNamespace, pipeline.Template, params, requestID)
		} else {
			runID, err = submitKubeflow(ctx, httpClient, kubeflowHost, pipeline.PipelineID, params, requestID)
		}

		if err != nil {
			slog.Error("pipeline submit failed", "pipeline", pipelineName, "error", err)
			return &messages.PipelineStatus{
				RequestId: requestID,
				Status:    "error",
				Error:     err.Error(),
			}, nil
		}

		result := &messages.PipelineStatus{
			RequestId:   requestID,
			Status:      "submitted",
			RunId:       runID,
			Engine:      pipeline.Engine,
			Pipeline:    pipelineName,
			SubmittedAt: time.Now().UTC().Format(time.RFC3339),
		}

		// Publish status update
		_ = h.NATS.Publish(fmt.Sprintf("ai.pipeline.status.%s", requestID), result)

		slog.Info("pipeline submitted", "pipeline", pipelineName, "run_id", runID)
		return result, nil
	})

	if err := h.Run(); err != nil {
		slog.Error("handler failed", "error", err)
	}
}

func submitArgo(ctx context.Context, client *http.Client, host, namespace, template string, params map[string]string, requestID string) (string, error) {
	argoParams := make([]map[string]string, 0, len(params))
	for k, v := range params {
		argoParams = append(argoParams, map[string]string{"name": k, "value": v})
	}

	workflow := map[string]any{
		"apiVersion": "argoproj.io/v1alpha1",
		"kind":       "Workflow",
		"metadata": map[string]any{
			"generateName": template + "-",
			"namespace":    namespace,
			"labels":       map[string]string{"request-id": requestID},
		},
		"spec": map[string]any{
			"workflowTemplateRef": map[string]string{"name": template},
			"arguments":           map[string]any{"parameters": argoParams},
		},
	}

	body, _ := json.Marshal(map[string]any{"workflow": workflow})
	url := fmt.Sprintf("%s/api/v1/workflows/%s", host, namespace)

	req, err := http.NewRequestWithContext(ctx, http.MethodPost, url, bytes.NewReader(body))
	if err != nil {
		return "", err
	}
	req.Header.Set("Content-Type", "application/json")

	resp, err := client.Do(req)
	if err != nil {
		return "", fmt.Errorf("argo request: %w", err)
	}
	defer func() { _ = resp.Body.Close() }()
	respBody, _ := io.ReadAll(resp.Body)

	if resp.StatusCode >= 400 {
		return "", fmt.Errorf("argo %d: %s", resp.StatusCode, string(respBody))
	}

	var result struct {
		Metadata struct {
			Name string `json:"name"`
		} `json:"metadata"`
	}
	if err := json.Unmarshal(respBody, &result); err != nil {
		return "", err
	}
	return result.Metadata.Name, nil
}

func submitKubeflow(ctx context.Context, client *http.Client, host, pipelineID string, params map[string]string, requestID string) (string, error) {
	kfParams := make([]map[string]string, 0, len(params))
	for k, v := range params {
		kfParams = append(kfParams, map[string]string{"name": k, "value": v})
	}

	runRequest := map[string]any{
		"name": fmt.Sprintf("%s-%s", pipelineID, requestID[:min(8, len(requestID))]),
		"pipeline_spec": map[string]any{
			"pipeline_id": pipelineID,
			"parameters":  kfParams,
		},
	}

	body, _ := json.Marshal(runRequest)
	url := fmt.Sprintf("%s/apis/v1beta1/runs", host)

	req, err := http.NewRequestWithContext(ctx, http.MethodPost, url, bytes.NewReader(body))
	if err != nil {
		return "", err
	}
	req.Header.Set("Content-Type", "application/json")

	resp, err := client.Do(req)
	if err != nil {
		return "", fmt.Errorf("kubeflow request: %w", err)
	}
	defer func() { _ = resp.Body.Close() }()
	respBody, _ := io.ReadAll(resp.Body)

	if resp.StatusCode >= 400 {
		return "", fmt.Errorf("kubeflow %d: %s", resp.StatusCode, string(respBody))
	}

	var result struct {
		Run struct {
			ID string `json:"id"`
		} `json:"run"`
	}
	if err := json.Unmarshal(respBody, &result); err != nil {
		return "", err
	}
	return result.Run.ID, nil
}

// Helpers

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