package functions

import (
	"bytes"
	"encoding/json"
	"fmt"
	"io"
	"text/tabwriter"
	"time"

	"github.com/spf13/cobra"
)

var (
	triggerTopic    string
	triggerSchedule string
)

// TriggersCmd is the parent command for trigger management.
var TriggersCmd = &cobra.Command{
	Use:   "triggers",
	Short: "Manage function PubSub and cron triggers",
	Long: `Add, list, and delete triggers for your serverless functions.

PubSub: when a message is published to a topic, every function with a
matching trigger is invoked with the message as input.

Cron: a function is invoked on a schedule (5-field crontab, or 6-field
crontab with a leading seconds column).

Examples:
  orama function triggers add my-function --topic calls:invite
  orama function triggers add my-function --schedule "0 3 * * *"
  orama function triggers add my-function --schedule "*/30 * * * * *"
  orama function triggers list my-function
  orama function triggers delete my-function <trigger-id>`,
}

// TriggersAddCmd adds a PubSub or Cron trigger to a function.
var TriggersAddCmd = &cobra.Command{
	Use:   "add <function-name>",
	Short: "Add a PubSub or Cron trigger",
	Long: `Registers a trigger that invokes the function automatically.

Pass exactly one of --topic (PubSub) or --schedule (cron). Schedules
accept either 5-field crontab (minute hour dom month dow) or 6-field
with seconds (sec minute hour dom month dow).`,
	Args: cobra.ExactArgs(1),
	RunE: runTriggersAdd,
}

// TriggersListCmd lists triggers for a function.
var TriggersListCmd = &cobra.Command{
	Use:   "list <function-name>",
	Short: "List triggers for a function",
	Args:  cobra.ExactArgs(1),
	RunE:  runTriggersList,
}

// TriggersDeleteCmd deletes a trigger.
var TriggersDeleteCmd = &cobra.Command{
	Use:   "delete <function-name> <trigger-id>",
	Short: "Delete a trigger",
	Args:  cobra.ExactArgs(2),
	RunE:  runTriggersDelete,
}

func init() {
	TriggersCmd.AddCommand(TriggersAddCmd)
	TriggersCmd.AddCommand(TriggersListCmd)
	TriggersCmd.AddCommand(TriggersDeleteCmd)

	TriggersAddCmd.Flags().StringVar(&triggerTopic, "topic", "", "PubSub topic to trigger on")
	TriggersAddCmd.Flags().StringVar(&triggerSchedule, "schedule", "", "Cron expression to trigger on (e.g. \"0 3 * * *\")")
	TriggersAddCmd.MarkFlagsMutuallyExclusive("topic", "schedule")
	TriggersAddCmd.MarkFlagsOneRequired("topic", "schedule")
}

func runTriggersAdd(cmd *cobra.Command, args []string) error {
	funcName := args[0]

	body, _ := json.Marshal(map[string]string{
		"topic":           triggerTopic,
		"cron_expression": triggerSchedule,
	})

	resp, err := apiRequest("POST", "/v1/functions/"+funcName+"/triggers", bytes.NewReader(body), "application/json")
	if err != nil {
		return err
	}
	defer resp.Body.Close()

	respBody, err := io.ReadAll(resp.Body)
	if err != nil {
		return fmt.Errorf("failed to read response: %w", err)
	}

	if resp.StatusCode != 201 && resp.StatusCode != 200 {
		return fmt.Errorf("API error (%d): %s", resp.StatusCode, string(respBody))
	}

	var result map[string]interface{}
	if err := json.Unmarshal(respBody, &result); err != nil {
		return fmt.Errorf("failed to parse response: %w", err)
	}

	if triggerSchedule != "" {
		fmt.Printf("Trigger added: cron(%s) → %s (id: %s)\n", triggerSchedule, funcName, result["trigger_id"])
	} else {
		fmt.Printf("Trigger added: %s → %s (id: %s)\n", triggerTopic, funcName, result["trigger_id"])
	}
	return nil
}

func runTriggersList(cmd *cobra.Command, args []string) error {
	funcName := args[0]

	result, err := apiGet("/v1/functions/" + funcName + "/triggers")
	if err != nil {
		return err
	}

	triggers, _ := result["triggers"].([]interface{})
	if len(triggers) == 0 {
		fmt.Printf("No triggers for function %q.\n", funcName)
		return nil
	}

	w := tabwriter.NewWriter(cmd.OutOrStdout(), 0, 0, 2, ' ', 0)
	// Bug #65 audit: the previous CLI rendered only ID/TOPIC/ENABLED, so cron
	// triggers appeared as mystery blank-topic rows. The handler returns a
	// `kind` discriminator plus pubsub-only `topic` or cron-only
	// `cron_expression` / `next_run_at` / `last_run_at`; the CLI now renders
	// both kinds in a single unified table.
	fmt.Fprintln(w, "ID\tKIND\tSCHEDULE/TOPIC\tNEXT RUN\tLAST RUN\tENABLED")
	for _, t := range triggers {
		tr, ok := t.(map[string]interface{})
		if !ok {
			continue
		}
		id := stringField(tr, "id", "ID")
		kind := stringField(tr, "kind", "Kind")
		// Backward compat: pre-#65 servers returned only `topic` with no
		// `kind` field. Treat those as pubsub.
		if kind == "" {
			kind = "pubsub"
		}

		var what, nextRun, lastRun string
		switch kind {
		case "cron":
			what = stringField(tr, "cron_expression", "CronExpression")
			nextRun = formatCronTimestamp(tr["next_run_at"])
			lastRun = formatCronTimestamp(tr["last_run_at"])
		default: // pubsub or unknown
			what = stringField(tr, "topic", "Topic")
			nextRun = "-"
			lastRun = "-"
		}

		enabled := true
		if e, ok := tr["Enabled"].(bool); ok {
			enabled = e
		} else if e, ok := tr["enabled"].(bool); ok {
			enabled = e
		}
		fmt.Fprintf(w, "%s\t%s\t%s\t%s\t%s\t%v\n", id, kind, what, nextRun, lastRun, enabled)
	}
	w.Flush()
	return nil
}

// stringField pulls a string from a JSON-decoded map under any of the
// supplied keys, in order. The handler emits snake_case (`cron_expression`)
// while older Go-tagged structs may surface PascalCase — try both.
func stringField(m map[string]interface{}, keys ...string) string {
	for _, k := range keys {
		if v, ok := m[k].(string); ok && v != "" {
			return v
		}
	}
	return ""
}

// formatCronTimestamp renders a JSON timestamp from the handler in a compact
// human-readable form. Returns "-" for nil / unparseable values so the CLI
// table stays aligned for never-run / pubsub rows.
func formatCronTimestamp(v interface{}) string {
	if v == nil {
		return "-"
	}
	s, ok := v.(string)
	if !ok || s == "" {
		return "-"
	}
	// Try RFC3339 first (Go's default time.Time JSON encoding); fall back to
	// the raw string so unexpected formats don't disappear silently.
	if ts, err := time.Parse(time.RFC3339, s); err == nil {
		return ts.UTC().Format("2006-01-02 15:04:05 UTC")
	}
	if ts, err := time.Parse(time.RFC3339Nano, s); err == nil {
		return ts.UTC().Format("2006-01-02 15:04:05 UTC")
	}
	return s
}

func runTriggersDelete(cmd *cobra.Command, args []string) error {
	funcName := args[0]
	triggerID := args[1]

	result, err := apiDelete("/v1/functions/" + funcName + "/triggers/" + triggerID)
	if err != nil {
		return err
	}

	if msg, ok := result["message"]; ok {
		fmt.Println(msg)
	} else {
		fmt.Println("Trigger deleted.")
	}
	return nil
}