// Package ws provides WebSocket handling for the API
package ws

import (
	"encoding/hex"
	"encoding/json"
	"fmt"
	"os"
	"path/filepath"
	"strings"
	"time"

	"github.com/gorilla/websocket"
	"github.com/jfraeys/fetch_ml/internal/queue"
	"github.com/jfraeys/fetch_ml/internal/worker/integrity"
)

func (h *Handler) populateExperimentIntegrityMetadata(
	task *queue.Task,
	commitIDHex string,
) (string, error) {
	if h.expManager == nil {
		return "", nil
	}

	// Validate commit ID (defense-in-depth)
	if len(commitIDHex) != 40 {
		return "", fmt.Errorf("invalid commit id length")
	}
	if _, err := hex.DecodeString(commitIDHex); err != nil {
		return "", fmt.Errorf("invalid commit id format")
	}

	filesPath := h.expManager.GetFilesPath(commitIDHex)

	depsName, err := selectDependencyManifest(filesPath)
	if err != nil {
		return "", err
	}

	if depsName != "" {
		task.Metadata["deps_manifest_name"] = depsName

		depsPath := filepath.Join(filesPath, depsName)
		if sha, err := integrity.FileSHA256Hex(depsPath); err == nil {
			task.Metadata["deps_manifest_sha256"] = sha
		}
	}

	basePath := filepath.Clean(h.expManager.BasePath())
	manifestPath := filepath.Join(basePath, commitIDHex, "manifest.json")
	manifestPath = filepath.Clean(manifestPath)

	if !strings.HasPrefix(manifestPath, basePath+string(os.PathSeparator)) {
		return "", fmt.Errorf("path traversal detected")
	}

	if data, err := os.ReadFile(manifestPath); err == nil {
		var man struct {
			OverallSHA string `json:"overall_sha"`
		}

		if err := json.Unmarshal(data, &man); err == nil && man.OverallSHA != "" {
			task.Metadata["experiment_manifest_overall_sha"] = man.OverallSHA
		}
	}

	return depsName, nil
}

// handleQueueJob handles the QueueJob opcode (0x01)
func (h *Handler) handleQueueJob(conn *websocket.Conn, payload []byte) error {
	// Parse payload: [opcode:1][api_key_hash:16][commit_id:20][priority:1][job_name_len:1][job_name:var]
	if len(payload) < 39 {
		return h.sendErrorPacket(conn, ErrorCodeInvalidRequest, "payload too short", "")
	}

	commitIDBytes := payload[17:37]
	commitIDHex := hex.EncodeToString(commitIDBytes)
	priority := payload[37]
	jobNameLen := int(payload[38])

	if len(payload) < 39+jobNameLen {
		return h.sendErrorPacket(conn, ErrorCodeInvalidRequest, "job_name length mismatch", "")
	}
	jobName := string(payload[39 : 39+jobNameLen])

	// Parse optional resource fields
	cpu, memoryGB, gpu, gpuMemory := 0, 0, 0, ""
	pos := 39 + jobNameLen
	if len(payload) > pos {
		cpu = int(payload[pos])
		pos++
		if len(payload) > pos {
			memoryGB = int(payload[pos])
			pos++
			if len(payload) > pos {
				gpu = int(payload[pos])
				pos++
				if len(payload) > pos {
					gpuMemLen := int(payload[pos])
					pos++
					if len(payload) >= pos+gpuMemLen {
						gpuMemory = string(payload[pos : pos+gpuMemLen])
					}
				}
			}
		}
	}

	task := &queue.Task{
		ID:        fmt.Sprintf("task-%d", time.Now().UnixNano()),
		JobName:   jobName,
		Status:    "queued",
		Priority:  int64(priority),
		CreatedAt: time.Now(),
		UserID:    "user",
		CreatedBy: "user",
		CPU:       cpu,
		MemoryGB:  memoryGB,
		GPU:       gpu,
		GPUMemory: gpuMemory,
		Metadata:  map[string]string{"commit_id": commitIDHex},
	}

	if _, err := h.populateExperimentIntegrityMetadata(task, commitIDHex); err != nil {
		return h.sendErrorPacket(
			conn, ErrorCodeInvalidRequest, "failed to resolve experiment metadata", err.Error(),
		)
	}

	if h.taskQueue != nil {
		if err := h.taskQueue.AddTask(task); err != nil {
			return h.sendErrorPacket(conn, ErrorCodeServerOverloaded, "failed to queue task", err.Error())
		}
	}

	return h.sendSuccessPacket(conn, map[string]any{"task_id": task.ID})
}

// handleQueueJobWithSnapshot handles the QueueJobWithSnapshot opcode (0x17)
func (h *Handler) handleQueueJobWithSnapshot(conn *websocket.Conn, payload []byte) error {
	if len(payload) < 41 {
		return h.sendErrorPacket(conn, ErrorCodeInvalidRequest, "payload too short", "")
	}

	commitIDBytes := payload[17:37]
	commitIDHex := hex.EncodeToString(commitIDBytes)
	priority := payload[37]
	jobNameLen := int(payload[38])

	if len(payload) < 39+jobNameLen {
		return h.sendErrorPacket(conn, ErrorCodeInvalidRequest, "job_name length mismatch", "")
	}
	jobName := string(payload[39 : 39+jobNameLen])

	pos := 39 + jobNameLen
	snapshotIDLen := int(payload[pos])
	pos++
	snapshotID := string(payload[pos : pos+snapshotIDLen])
	pos += snapshotIDLen
	snapshotSHALen := int(payload[pos])
	pos++
	snapshotSHA := string(payload[pos : pos+snapshotSHALen])

	task := &queue.Task{
		ID:         fmt.Sprintf("task-%d", time.Now().UnixNano()),
		JobName:    jobName,
		Status:     "queued",
		Priority:   int64(priority),
		CreatedAt:  time.Now(),
		UserID:     "user",
		CreatedBy:  "user",
		SnapshotID: snapshotID,
		Metadata: map[string]string{
			"commit_id":       commitIDHex,
			"snapshot_sha256": snapshotSHA,
		},
	}

	if _, err := h.populateExperimentIntegrityMetadata(task, commitIDHex); err != nil {
		return h.sendErrorPacket(
			conn, ErrorCodeInvalidRequest, "failed to resolve experiment metadata", err.Error(),
		)
	}

	if h.taskQueue != nil {
		if err := h.taskQueue.AddTask(task); err != nil {
			return h.sendErrorPacket(conn, ErrorCodeServerOverloaded, "failed to queue task", err.Error())
		}
	}

	return h.sendSuccessPacket(conn, map[string]any{"task_id": task.ID})
}

// handleCancelJob handles the CancelJob opcode (0x03)
func (h *Handler) handleCancelJob(conn *websocket.Conn, payload []byte) error {
	if len(payload) < 18 {
		return h.sendErrorPacket(conn, ErrorCodeInvalidRequest, "payload too short", "")
	}

	jobNameLen := int(payload[17])
	if len(payload) < 18+jobNameLen {
		return h.sendErrorPacket(conn, ErrorCodeInvalidRequest, "job_name length mismatch", "")
	}
	jobName := string(payload[18 : 18+jobNameLen])

	if h.taskQueue != nil {
		task, err := h.taskQueue.GetTaskByName(jobName)
		if err == nil && task != nil {
			task.Status = "cancelled"
			if err := h.taskQueue.UpdateTask(task); err != nil {
				return h.sendErrorPacket(conn, ErrorCodeServerOverloaded, "failed to cancel task", err.Error())
			}
		}
	}

	return h.sendSuccessPacket(conn, map[string]any{"message": "Job cancelled"})
}

// handlePrune handles the Prune opcode (0x04)
func (h *Handler) handlePrune(conn *websocket.Conn, payload []byte) error {
	// Parse payload: [api_key_hash:16][prune_type:1][value:4]
	if len(payload) < 16+1+4 {
		return h.sendErrorPacket(conn, ErrorCodeInvalidRequest, "prune payload too short", "")
	}

	// Authenticate user
	// Skip 16-byte API key hash for now (authentication would use it)
	// offset := 16
	// pruneType := payload[offset]
	// value := binary.BigEndian.Uint32(payload[offset+1 : offset+5])

	return h.sendSuccessPacket(conn, map[string]any{"message": "Prune completed", "pruned": 0})
}