package cli

import (
	"context"
	"fmt"
	"io"

	"gitea.maximumdirect.net/eric/distributor/internal/app"
)

func pruneCommand(ctx context.Context, args []string, stdout, stderr io.Writer) int {
	if hasHelp(args) {
		printPruneHelp(stdout)
		return exitOK
	}

	flags := newFlagSet("prune", stderr)
	configPath := flags.String("config", "", "path to config file")
	pipelineID := flags.String("pipeline", "", "pipeline id")
	destinationID := flags.String("destination", "", "destination id")
	dryRun := flags.Bool("dry-run", false, "report planned deletes without deleting outputs or rewriting state")
	apply := flags.Bool("apply", false, "delete planned managed outputs and rewrite state")
	formatFlag := addFormatFlag(flags)
	if err := flags.Parse(args); err != nil {
		return exitUsage
	}
	if rejectPositionalArgs(stderr, "prune", flags.Args()) {
		return exitUsage
	}
	format, ok := parseOutputFormat(stderr, "prune", *formatFlag)
	if !ok {
		return exitUsage
	}
	if !validatePruneFlags(stderr, *configPath, *pipelineID, *destinationID, *dryRun, *apply) {
		return exitUsage
	}

	if _, err := app.Prune(ctx, app.PruneOptions{
		ConfigPath:    *configPath,
		PipelineID:    *pipelineID,
		DestinationID: *destinationID,
		DryRun:        *dryRun,
		Stdout:        stdout,
		OutputFormat:  format,
	}); err != nil {
		return fail(stderr, err)
	}
	return exitOK
}

func validatePruneFlags(stderr io.Writer, configPath, pipelineID, destinationID string, dryRun, apply bool) bool {
	if configPath == "" {
		fmt.Fprintf(stderr, "%s: prune requires --config\n", app.Name)
		return false
	}
	if pipelineID == "" {
		fmt.Fprintf(stderr, "%s: prune requires --pipeline\n", app.Name)
		return false
	}
	if destinationID == "" {
		fmt.Fprintf(stderr, "%s: prune requires --destination\n", app.Name)
		return false
	}
	if dryRun == apply {
		fmt.Fprintf(stderr, "%s: prune requires exactly one of --dry-run or --apply\n", app.Name)
		return false
	}
	return true
}

func printPruneHelp(w io.Writer) {
	fmt.Fprint(w, `Usage:
  distributor prune --config <path> --pipeline <id> --destination <id> (--dry-run|--apply) [--format text|json]

Options:
  --config <path>       Path to config file
  --pipeline <id>       Pipeline id that selects the destination root
  --destination <id>    Destination id that selects the destination root
  --dry-run             Report planned deletes without deleting outputs or rewriting state
  --apply               Delete planned managed outputs and rewrite state
  --format text|json    Output format

Prune reads the selected destination's configured retention policy and managed
state, then plans owner-scoped managed output deletion. --dry-run is read-only.
--apply deletes only planned managed output paths, preserves unmanaged files,
and rewrites state after confirmed deletes.
`)
}