package handler

import (
	"context"
	"database/sql"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"regexp"
	"strconv"
	"strings"
	"time"
	"vctp/db/queries"
	models "vctp/server/models"
)

// VmModify receives the CloudEvent for a VM modification or move
func (h *Handler) VmModify(w http.ResponseWriter, r *http.Request) {
	var configChanges []map[string]string
	params := queries.CreateUpdateParams{}
	var unixTimestamp int64

	reqBody, err := io.ReadAll(r.Body)
	if err != nil {
		h.Logger.Error("Invalid data received", "error", err)
		fmt.Fprintf(w, "Invalid data received")
		w.WriteHeader(http.StatusInternalServerError)
		return
	} else {
		h.Logger.Debug("received input data", "length", len(reqBody))
	}

	// Decode the JSON body into CloudEventReceived struct
	var event models.CloudEventReceived
	if err := json.Unmarshal(reqBody, &event); err != nil {
		h.Logger.Error("unable to decode json", "error", err)
		prettyPrint(reqBody)
		http.Error(w, "Invalid JSON body", http.StatusBadRequest)
		return
	} else {
		h.Logger.Debug("successfully decoded JSON")
		//prettyPrint(event)
	}

	if event.CloudEvent.Data.ConfigChanges == nil {
		h.Logger.Warn("Received event contains no config change")
		prettyPrint(event)
		w.WriteHeader(http.StatusAccepted)
		fmt.Fprintf(w, "Processed update event but no config changes were found\n")
	} else {
		h.Logger.Debug("Received event contains config change info")
		configChanges = h.processConfigChanges(event.CloudEvent.Data.ConfigChanges.Modified)
		//prettyPrint(configChanges)

		var found = false
		// Only interested in vCPU or ram changes currently
		for _, change := range configChanges {
			//fmt.Printf("Type: %s, New Value: %s\n", change["type"], change["newValue"])
			switch change["type"] {
			case "config.hardware.numCPU":
				i, err := strconv.ParseInt(change["newValue"], 10, 64)
				if err != nil {
					h.Logger.Error("Unable to convert new value to int64", "new_value", change["newValue"])
				} else {
					found = true
					params.NewVcpus = sql.NullInt64{Int64: i, Valid: i > 0}
				}
			case "config.hardware.memoryMB":
				i, err := strconv.ParseInt(change["newValue"], 10, 64)
				if err != nil {
					h.Logger.Error("Unable to convert new value to int64", "new_value", change["newValue"])
				} else {
					found = true
					params.NewRam = sql.NullInt64{Int64: i, Valid: i > 0}
				}
			}

			// Check if a disk was added (or maybe removed?)
			if strings.Contains(change["type"], "config.hardware.device") &&
				strings.Contains(event.CloudEvent.Data.FullFormattedMessage, ".vmdk") {

				// TODO - recalculate total disk size
				h.Logger.Debug("Detected config change for VM disk")
			}
		}

		// Only create a database record if we found one of the config changes we were interested in
		if found {
			// lookup Iid from Inventory table for this VM
			// also figure out what to do if we didn't find an entry for this VM in the Inventory table. Create one?
			h.Logger.Debug("Checking inventory table for VM record")
			invParams := queries.GetInventoryVmIdParams{
				VmId:           sql.NullString{String: event.CloudEvent.Data.VM.VM.Value, Valid: event.CloudEvent.Data.VM.VM.Value != ""},
				DatacenterName: sql.NullString{String: event.CloudEvent.Data.Datacenter.Name, Valid: event.CloudEvent.Data.Datacenter.Name != ""},
			}
			invResult, err := h.Database.Queries().GetInventoryVmId(context.Background(), invParams)

			if err != nil {
				h.Logger.Error("unable to find existing inventory record for this VM", "error", err)
				// TODO - how to handle?
			} else {
				params.InventoryId = sql.NullInt64{Int64: invResult.Iid, Valid: invResult.Iid > 0}
			}

			// Parse the datetime string to a time.Time object
			eventTime, err := time.Parse(time.RFC3339, event.CloudEvent.Data.CreatedTime)
			if err != nil {
				h.Logger.Warn("unable to convert cloud event time to timestamp", "error", err)
				unixTimestamp = time.Now().Unix()
			} else {
				// Convert to Unix timestamp
				unixTimestamp = eventTime.Unix()
			}

			// populate other parameters for the Update database record
			params.EventId = sql.NullString{String: event.CloudEvent.ID, Valid: event.CloudEvent.ID != ""}
			params.EventKey = sql.NullString{String: strconv.Itoa(event.CloudEvent.Data.Key), Valid: event.CloudEvent.Data.Key > 0}
			params.UpdateTime = sql.NullInt64{Int64: unixTimestamp, Valid: unixTimestamp > 0}
			params.UpdateType = "reconfigure"

			// Create the Update database record
			result, err := h.Database.Queries().CreateUpdate(context.Background(), params)
			if err != nil {
				h.Logger.Error("unable to perform database insert", "error", err)
				w.WriteHeader(http.StatusInternalServerError)
				fmt.Fprintf(w, "Error : %v\n", err)
				return
			} else {
				h.Logger.Debug("created database record", "insert_result", result)
				w.WriteHeader(http.StatusOK)
				fmt.Fprintf(w, "Processed update event: %v\n", result)
				return
			}
		} else {
			w.WriteHeader(http.StatusAccepted)
			fmt.Fprintf(w, "Processed update event but no config changes were of interest\n")
			prettyPrint(configChanges)
		}
	}
}

func (h *Handler) processConfigChanges(configChanges string) []map[string]string {
	// Split the string on one or more consecutive newline characters
	changes := regexp.MustCompile(`\n+`).Split(configChanges, -1)

	// Regular expression to match config type and the new value after '->' or '<-'
	re := regexp.MustCompile(`(?P<type>[^\s]+): [^\s]+ -[><] (?P<newValue>[^;]+);`)

	// Result will hold a list of changes with type and new value
	var result []map[string]string

	for _, change := range changes {
		// Trim any extra spaces and skip empty lines
		change = strings.TrimSpace(change)
		//h.Logger.Debug("Processing config change element", "substring", change)
		if change == "" {
			continue
		}

		// Find the matches using the regex
		match := re.FindStringSubmatch(change)
		if len(match) > 0 {
			// Create a map with 'type' and 'newValue'
			changeMap := map[string]string{
				"type":     match[1], // config type
				"newValue": match[2], // new value after -> or <-
			}
			//h.Logger.Debug("Adding new entry to output", "map", changeMap)
			result = append(result, changeMap)
		} else {
			h.Logger.Warn("No regex matches for string", "input", change)
		}
	}

	return result
}