package cli

import (
	"flag"
	"fmt"
	"os"
	"path/filepath"

	"git.vakhrushev.me/av/convy/internal/lang"
	"git.vakhrushev.me/av/convy/internal/manifest"
)

// manifestSkeleton is what a suite starts as. The tables stand empty but
// present: `convy suite add` splices entries into them, and a table that is not
// there is a table an edit cannot find.
//
// The two documents about the language are left commented out on purpose. The
// suite is expected to carry them, but the tool cannot author them, and a
// manifest pointing at a file that does not exist is a manifest that fails its
// own check on the first run.
const manifestSkeleton = `# The manifest of a conventions suite.
#
# Two manifests exist in the model, each named after what it describes:
# suite.toml here, in the suite, describes the suite itself; .conventions.toml
# in a project describes what that project subscribed to. Which of the two lies
# next to you tells you where you are.

[language]
version = %d
lang = "%s"
# description = "LANGUAGE.md"  # the full account of the language, stays with the author
# reading = "READING.md"       # the short guide for a reader, travels into every copy

# ─── Topics ─────────────────────────────────────────────────────────────────
#
# A topic is a set of rules about one focus of development, and the unit of
# subscription. The value is the one line about what the topic is for; the
# table of conventions in a consumer's README is built out of it.

[topics.live]

# Retired names land here together with a reason and a date, so that they can
# never be handed to another topic: the name lives on in foreign repositories.

[topics.retired]

# ─── Rule prefixes ──────────────────────────────────────────────────────────
#
# A prefix is four uppercase Latin letters, unique across the suite, chosen for
# a file rather than derived by a formula. The letter X is reserved for the
# local rules of consumers and is never taken here. Paths are given from the
# root of the repository.

[prefixes.live]

# Prefixes of deleted and split files land here, likewise never to be reissued.

[prefixes.retired]
`

func runSuiteInit(env Env, args []string) ExitCode {
	fs := flag.NewFlagSet("convy suite init", flag.ContinueOnError)
	fs.SetOutput(env.Err)
	path := fs.String("path", "", "directory of the suite; it is created if absent")
	code := fs.String("lang", "", "code of the natural language the suite is written in")
	version := fs.Int("language-version", 1, "version of the conventions language")
	if err := fs.Parse(args); err != nil {
		return Usage
	}

	fields := []Field{{
		Flag:    "path",
		Ask:     "Directory of the suite",
		Hint:    "Where the suite will live. The directory is created if it is not there yet.",
		Default: ".",
	}, {
		Flag:    "lang",
		Ask:     "Natural language of the suite",
		Hint:    "The language the rules are written in. It settles the key words: ДОЛЖЕН and ПОЧЕМУ for ru, MUST and WHY for en.",
		Default: manifest.DefaultLanguageCode,
		Check: func(v string) error {
			_, err := lang.Lookup(*version, v)
			return err
		},
	}}

	given := map[string]string{"path": *path, "lang": *code}
	if len(args) == 0 {
		if !env.Interactive {
			fmt.Fprintln(env.Err, "convy suite init without arguments asks questions, and there is no terminal to ask on; pass --path and --lang")
			return Usage
		}
		if err := askAll(env, fields, given); err != nil {
			return Usage
		}
	} else if err := resolve(fields, given); err != nil {
		fmt.Fprintln(env.Err, err)
		return Usage
	}

	root := given["path"]
	if _, err := os.Stat(filepath.Join(root, manifest.Name)); err == nil {
		fmt.Fprintf(env.Err, "%s already holds %s: this is a suite already\n", root, manifest.Name)
		return Usage
	}
	if err := os.MkdirAll(filepath.Join(root, "conventions"), 0o755); err != nil {
		fmt.Fprintln(env.Err, err)
		return Usage
	}

	body := fmt.Sprintf(manifestSkeleton, *version, given["lang"])
	name := filepath.Join(root, manifest.Name)
	if err := os.WriteFile(name, []byte(body), 0o644); err != nil {
		fmt.Fprintln(env.Err, err)
		return Usage
	}

	fmt.Fprintf(env.Out, "\ncreated %s\ncreated %s\n", name, filepath.Join(root, "conventions"))
	fmt.Fprintf(env.Out, "\nthe suite speaks %s, conventions language version %d\n", given["lang"], *version)
	fmt.Fprint(env.Out, `
next:
  write the two documents about the language and name them in [language]
  convy suite add    add the first convention
  convy suite check  verify the suite holds together
`)
	return OK
}

// askAll walks the fields in interactive mode, keeping answers already given on
// the command line.
func askAll(env Env, fields []Field, given map[string]string) error {
	d := newDialogue(env)
	for _, f := range fields {
		if given[f.Flag] != "" {
			continue
		}
		answer, err := d.ask(f)
		if err != nil {
			fmt.Fprintln(env.Err, "\ninterrupted, nothing was written")
			return err
		}
		given[f.Flag] = answer
	}
	return nil
}