// loomctl fetches documents this repository depends on, and finds out when they
// change.
//
// It reports and never repairs. Everything it writes, it writes to the working
// tree — committing and pushing are yours, because the consequences of a push
// land on people a tool cannot experience.
package main

import (
	"flag"
	"fmt"
	"os"

	"git.hypertheory-labs.dev/loom/loom-cli/internal/external"
)

const usage = `loomctl — fetch what you depend on, and find out when it changed.

  loomctl external list <repo-url>       what a repository publishes
  loomctl external add <url> [--path p]  adopt one document and lock it
  loomctl external check                 ask every publisher whether theirs moved
  loomctl external apply [path...]       move a staged polad into place, lock and all

check reports and does not fix. A document that moved is staged as a polad in
.loom/cart/current/polad/ — a candidate shaped exactly like what it would
become — and somebody decides. Its exits are apply or discard; nothing there
drifts into being kept. With no cart open, check says what moved and stages
nothing, because opening a round is somebody's act and not a side effect.

add adopts what is not here yet, and refuses what is already adopted. Given a
document that is present but unlocked — fetched by hand before this existed —
it supplies the missing origin: identical bytes lock it, differing bytes are
staged, and the local copy is never overwritten, because a copy that differs is
the only evidence that anything moved while nothing was watching.

Adopted documents live in .loom/externals/<host>/<owner>/<repo>/<name>.md, and
their origins in .loom/externals/.locks. The path is for a person to read; the
lock is what a machine uses, because the path does not round-trip to a URL.

Credentials are read-only and per host, in ~/.config/loomctl/config.json or in
LOOMCTL_TOKEN_<HOST>. loomctl never writes over the network, so a token it is
given should never carry write scope.

Requires git on PATH, for list only.
`

func main() {
	if err := run(os.Args[1:]); err != nil {
		fmt.Fprintln(os.Stderr, "loomctl: "+err.Error())
		os.Exit(1)
	}
}

func run(args []string) error {
	if len(args) == 0 || args[0] == "-h" || args[0] == "--help" || args[0] == "help" {
		fmt.Print(usage)
		return nil
	}
	switch args[0] {
	case "external":
		return runExternal(args[1:])
	default:
		return fmt.Errorf("unknown command %q\n\n%s", args[0], usage)
	}
}

func runExternal(args []string) error {
	if len(args) == 0 {
		return fmt.Errorf("external needs a subcommand: list, add, check, apply")
	}
	switch args[0] {
	case "list":
		if len(args) != 2 {
			return fmt.Errorf("usage: loomctl external list <repo-url>")
		}
		return external.List(args[1], os.Stdout)

	case "add":
		fs := flag.NewFlagSet("add", flag.ContinueOnError)
		path := fs.String("path", "", "where to keep it, relative to .loom/externals (default: derived from the URL)")
		if err := fs.Parse(args[1:]); err != nil {
			return err
		}
		if fs.NArg() != 1 {
			return fmt.Errorf("usage: loomctl external add <url> [--path p]")
		}
		root, err := root()
		if err != nil {
			return err
		}
		return external.Add(root, fs.Arg(0), *path, os.Stdout)

	case "check":
		root, err := root()
		if err != nil {
			return err
		}
		return external.Check(root, os.Stdout)

	case "apply":
		root, err := root()
		if err != nil {
			return err
		}
		return external.Apply(root, args[1:], os.Stdout)

	default:
		return fmt.Errorf("unknown external subcommand %q", args[0])
	}
}

func root() (string, error) {
	wd, err := os.Getwd()
	if err != nil {
		return "", err
	}
	return external.FindRoot(wd)
}