// 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"
	"io"
	"os"
	"sort"
	"strings"

	"git.hypertheory-labs.dev/loom/loom-cli/internal/config"

	"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 <owner/repo>     what a repository publishes
  loomctl external add <owner/repo> <doc>  adopt one document and lock it
  loomctl external add <url> [--path p]    ... or by its full raw URL
  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.

loomctl grants no access. It reads what your credentials already let you read,
and records where the copy came from — which is the part copy-and-paste loses.
It warns rather than refuses: adopting from a source less readable than the
repository you are adopting into is yours to decide, and the check only tells
public from not-public, so it cannot see two repositories private to different
people.

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.

  loomctl config                         which context is current, and from where

A bare owner/repo is resolved against the current context in
~/.config/loomctl/config.json, which holds a host, its flavor and a read-only
token. The host's raw-file route lives there so that nobody has to type it, and
LOOMCTL_TOKEN_<HOST> overrides the file for one invocation. loomctl never writes
over the network, so a token it is given should never carry write scope.

    {
      "current-context": "hypertheory",
      "contexts": {
        "hypertheory": {
          "host": "git.hypertheory-labs.dev",
          "flavor": "gitea",
          "token": "..."
        }
      }
    }

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:])
	case "config":
		return showConfig(os.Stdout)
	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 <owner/repo>")
		}
		if strings.Contains(args[1], "://") {
			return external.List(args[1], os.Stdout)
		}
		return external.ListByName(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
		}
		root, err := root()
		if err != nil {
			return err
		}
		switch fs.NArg() {
		case 1:
			if !strings.Contains(fs.Arg(0), "://") {
				return fmt.Errorf("adopting by name needs the document too: " +
					"loomctl external add <owner/repo> <doc>")
			}
			return external.Add(root, fs.Arg(0), *path, os.Stdout)
		case 2:
			return external.AddByName(root, fs.Arg(0), fs.Arg(1), os.Stdout)
		default:
			return fmt.Errorf("usage: loomctl external add <owner/repo> <doc>, " +
				"or loomctl external add <url> [--path p]")
		}

	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])
	}
}

// showConfig says which context is current and where it came from, so that "my
// token is not being used" is answerable without printing the token.
func showConfig(out io.Writer) error {
	cfg, err := config.Load()
	if err != nil {
		return err
	}
	fmt.Fprintf(out, "config   %s\n", config.Path())
	if len(cfg.Contexts) == 0 {
		fmt.Fprintln(out, "         (none — public repositories still work by full URL)")
		return nil
	}
	names := make([]string, 0, len(cfg.Contexts))
	for n := range cfg.Contexts {
		names = append(names, n)
	}
	sort.Strings(names)
	for _, n := range names {
		c := cfg.Contexts[n]
		marker := " "
		if n == cfg.CurrentContext {
			marker = "*"
		}
		flavor := c.Flavor
		if flavor == "" {
			flavor = "gitea (default)"
		}
		fmt.Fprintf(out, "%s %-14s %-32s %-16s %s\n", marker, n, c.Host, flavor, credential(cfg, c))
	}
	if _, err := cfg.Current(); err != nil {
		fmt.Fprintf(out, "\n%v\n", err)
	}
	return nil
}

func credential(cfg *config.Config, c config.Context) string {
	if os.Getenv("LOOMCTL_TOKEN") != "" {
		return "token from LOOMCTL_TOKEN"
	}
	if cfg.TokenFor(c.Host) != "" {
		if c.Token == "" {
			return "token from the environment"
		}
		return "token set"
	}
	return "no token (anonymous)"
}

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