package cmd

import (
	"fmt"
	"log"
	"slices"
	"time"

	"github.com/Jaculabilis/intake/core"
	"github.com/spf13/cobra"
)

var fetchCmd = &cobra.Command{
	Use:   "fetch [--source name] [-n|--dry-run] [--env NAME-VALUE [-- env NAME=VALUE ...]] [-- argv...]",
	Short: "Fetch items for a source and update the feed",
	Long: fmt.Sprintf(`Fetch items for a source and update the feed.

Items returned by a successful fetch will be used to update the source.
A fetch is successful if all items output by the fetch are parsed successfully
and the exit code is 0. No changes will be made to the source if the fetch
does not succeed.

By default, fetch uses the configured "fetch" action on the specified source.
You can provide an alternative argv, execute as a dry run to make no changes,
or execute an argv outside of a source to test it. If a source is not specified,
a dry run is implied.

In a dry run, the items will be printed according to the chosen format and
the source will not be updated with the fetch result.

Source-level behavior configured by environment variables, such as INTAKE_TTL,
will not be applied by --env.

%s`, makeFormatHelpText()),
	Example: `  Fetch items for a source:
      intake fetch --source name

  Fetch for a source using an alternative fetch action:
      intake fetch --source name -- command args

  Test a fetch action in isolation:
      intake fetch -- command args

  Test a fetch action with a source's state and environment:
      intake fetch --source name --dry-run -- command args`,
	Run: func(cmd *cobra.Command, args []string) {
		fetch(
			stringArg(cmd, "source"),
			stringArrayArg(cmd, "env"),
			stringArg(cmd, "format"),
			stringArg(cmd, "timeout"),
			boolArg(cmd, "dry-run"),
			getArgv(cmd, args),
		)
	},
	DisableFlagsInUseLine: true,
}

func init() {
	rootCmd.AddCommand(fetchCmd)

	fetchCmd.Flags().StringP("source", "s", "", "Source name to fetch (required)")
	fetchCmd.Flags().StringArrayP("env", "e", nil, "Environment variables to set, in the form KEY=VAL")
	fetchCmd.Flags().BoolP("dry-run", "n", false, "Do not update the source with the fetch results")
	fetchCmd.Flags().StringP("format", "f", "headlines", "Feed format for returned items.")
	fetchCmd.Flags().StringP("timeout", "t", core.DefaultTimeout.String(), "Timeout duration")
}

func fetch(
	source string,
	envs []string,
	format string,
	timeout string,
	dryRun bool,
	argv []string,
) {
	formatter := formatAs(format)

	duration, err := time.ParseDuration(timeout)
	if err != nil {
		log.Fatalf("error: invalid duration: %v", err)
	}

	if source == "" && len(argv) == 0 {
		log.Fatal("Either --source or an argv must be provided")
	}

	// No source implies dry run because there's no source to update
	dryRun = dryRun || source == ""

	db := openAndMigrateDb()

	var fSource string
	var fArgv []string
	var fEnvs []string
	var fState []byte = nil

	if source == "" {
		fSource = "test"
		fArgv = argv
		fEnvs = envs
		fState = nil
	} else {
		sourceState, sourceEnvs, sourceArgv, err := core.GetSourceActionInputs(db, source, "fetch")
		if err != nil {
			log.Fatalf("error: failed to load data for %s: %v", source, err)
		}
		fSource = source
		if len(argv) > 0 {
			fArgv = argv
		} else {
			fArgv = sourceArgv
		}
		fEnvs = append(sourceEnvs, envs...)
		fState = sourceState
	}

	items, newState, errItem, err := core.Execute(fSource, fArgv, fEnvs, fState, "", duration)
	if err != nil {
		if !dryRun {
			core.AddErrorItem(db, errItem)
		}
		log.Fatalf("error: failed to execute fetch: %v", err)
	}

	if dryRun {
		log.Printf("fetch returned %d items", len(items))
		if !slices.Equal(fState, newState) {
			log.Printf("state update (%d => %d bytes)", len(fState), len(newState))
		}
		for _, item := range items {
			fmt.Println(formatter(item))
		}
		return
	}

	added, deleted, err := core.UpdateWithFetchedItems(db, source, newState, items, time.Now())
	if err != nil {
		log.Fatalf("error: failed to update: %v", err)
	}
	log.Printf("%s added %d items, updated %d items, and deleted %d items", source, added, len(items)-added, deleted)
}