package cmd

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

	"git.noodles.cam/claude-skills/marketplace/cli/internal/config"
	"git.noodles.cam/claude-skills/marketplace/cli/internal/project"
	"git.noodles.cam/claude-skills/marketplace/cli/internal/scaffold"
)

// initOptions is everything init does, as data.
//
// It exists so that --interactive and the flags are two ways of filling in one
// struct rather than two implementations of one command. Every question the
// wizard asks has a field here and therefore a flag: a step that could only be
// reached by answering a prompt would be a step no script, no CI run and no
// agent could take.
type initOptions struct {
	Root          string
	Login         string
	Repo          string
	Scaffold      bool
	ScaffoldOut   string
	MirrorHook    bool
	ForceSettings bool
	DryRun        bool
}

// writeConfig creates or updates .kettle/config.yaml, touching only the
// settings it was given.
//
// Init is idempotent, and that has to include the config: re-running it to add
// a repository must not silently drop the login somebody pinned last week.
func writeConfig(root, login, repo string, dryRun bool) (string, error) {
	path := filepath.Join(root, project.Marker, "config.yaml")
	rel := filepath.Join(project.Marker, "config.yaml")

	cfg, existed, err := config.ReadProjectFile(path)
	if err != nil {
		return "", err
	}
	changed := !existed
	if login != "" && cfg.Login != login {
		cfg.Login, changed = login, true
	}
	if repo != "" && cfg.Repo != repo {
		cfg.Repo, changed = repo, true
	}
	if !changed {
		return "", nil
	}

	verb := "updated"
	if !existed {
		verb = "created"
	}
	detail := "no login or repository pinned yet — `kettle init --login … --repo …`"
	if cfg.Login != "" || cfg.Repo != "" {
		detail = fmt.Sprintf("login: %s, repo: %s", orNone(cfg.Login), orNone(cfg.Repo))
	}
	if dryRun {
		return fmt.Sprintf("%s %s (%s)", verb, rel, detail), nil
	}
	if err := config.SaveProject(path, cfg); err != nil {
		return "", err
	}
	return fmt.Sprintf("%s %s (%s)", verb, rel, detail), nil
}

func orNone(s string) string {
	if s == "" {
		return "none"
	}
	return s
}

func init() {
	register(&Command{
		Name:  "init",
		Group: GroupProject,
		Short: "make this directory a project that tracks issues",
		Long: `Creates ` + "`.kettle/`" + ` — the marker every other command resolves the store from,
and ` + "`.kettle/config.yaml`" + `, which says which tracker repository these issues
belong to and which login to reach it under — and writes ` + "`.claude/`" + `: the slash
commands an operator invokes, the skills a model loads, and the runner subagent.

The marker is deliberately something an operator makes, not something inferred
from the tree: ` + "`.git`" + ` is in every clone, so anything that inferred a root from
one would write issues into whatever it happened to be installed in.

--login pins a name, never a credential. The tokens live in one file per
machine, outside every working tree, managed with ` + "`kettle auth`" + `.

All of it is idempotent: it creates .kettle/issues and .kettle/payload, migrates
an older store in if it finds one (either layout the tea plugin used, oldest
first), writes the config without disturbing settings it was not given, writes
the .claude/ tree, and adds .kettle/ to .gitignore. Each migration is a move,
not a copy — two stores is the state the marker exists to prevent — and it
refuses to pick a winner when both sides hold a file of the same name.

IT REFUSES TO RUN IN A LINKED WORKTREE, and names the main checkout instead. A
worktree is the same project on another branch and reaches the store by a hop
out to the main checkout; a marker here would give one project two stores, and
the directory holding the second one disappears with the branch.

--interactive walks a person through the whole thing — the login, the token with
the echo turned off, the repository, the .claude/ tree and the AGENTS.md mirror
hook. IT REQUIRES A TERMINAL and refuses a standard input that is not one, which
is deliberate: every question it asks has a flag beside it, so nothing that is
not a person ever needs to answer a prompt.`,
		Examples: []Example{
			{"kettle init", "initialize the current directory"},
			{"kettle init --interactive", "be walked through it, at a terminal"},
			{"kettle init --login noodles --repo claude-skills/marketplace", "and point it at a tracker"},
			{"kettle init --mirror-hook", "register the AGENTS.md mirror on PreToolUse(Bash)"},
			{"kettle init --at ~/code/x", "initialize somewhere else"},
			{"kettle init --dry-run", "say what it would do, touch nothing"},
		},
		Setup: func(fs *flag.FlagSet) func([]string) error {
			at := fs.String("at", "", "directory to initialize (default: the working directory)")
			login := fs.String("login", "", "name of a login in the machine-wide file (see `kettle auth`)")
			repo := fs.String("repo", "", "tracker repository, as owner/name")
			interactive := fs.Bool("interactive", false, "ask, one question at a time; requires a terminal")
			noScaffold := fs.Bool("no-scaffold", false, "do not write the .claude/ commands, skills and subagent")
			scaffoldOut := fs.String("scaffold-out", "", "where the .claude/ tree goes (default: <project>/"+scaffold.Marker+")")
			mirrorHook := fs.Bool("mirror-hook", false, "register `kettle mirror --hook` on PreToolUse(Bash)")
			forceSettings := fs.Bool("force-settings", false, "let the hook be merged into an existing settings.json, reformatting it")
			dryRun := fs.Bool("dry-run", false, "report what would happen; change nothing")

			return func(args []string) error {
				root := *at
				if root == "" {
					wd, err := os.Getwd()
					if err != nil {
						return err
					}
					root = wd
				}
				root, err := filepath.Abs(root)
				if err != nil {
					return err
				}
				if fi, err := os.Stat(root); err != nil || !fi.IsDir() {
					return Fail("%s is not a directory", root)
				}

				opts := initOptions{
					Root:          root,
					Login:         *login,
					Repo:          *repo,
					Scaffold:      !*noScaffold,
					ScaffoldOut:   *scaffoldOut,
					MirrorHook:    *mirrorHook,
					ForceSettings: *forceSettings,
					DryRun:        *dryRun,
				}
				if *interactive {
					if err := askInit(&opts); err != nil {
						return err
					}
				}
				return runInit(opts)
			}
		},
	})
}

func runInit(opts initOptions) error {
	// A worktree is the same project on another branch. The rule used to live in
	// a skill somebody had to read; it is here because the wizard is now the
	// front door and a front door cannot rely on the reader having read anything.
	if main := project.MainWorktree(opts.Root); main != "" {
		return Fail("%s is a linked worktree of the project at %s.\n"+
			"A worktree reaches that store on its own — the walk crosses to it through the `gitdir:` in the .git file — "+
			"and a marker here would give one project two stores, the second of which is deleted with the branch.\n"+
			"Initialize the main checkout instead: kettle init --at %s", opts.Root, main, main)
	}

	// A second marker inside an existing project gives it a second store, and
	// the nearer one wins — which is a surprise worth naming before it happens,
	// not after.
	if existing := project.Root(opts.Root); existing != "" && existing != opts.Root {
		fmt.Fprintf(os.Stderr,
			"warning: %s already sits inside the project at %s — a second marker here gives it a second store, and the nearer one wins.\n",
			opts.Root, existing)
	}

	if opts.Repo != "" {
		if owner, name, ok := strings.Cut(opts.Repo, "/"); !ok || owner == "" || name == "" {
			return Fail("--repo %q is not owner/name", opts.Repo)
		}
	}

	done, err := project.Init(opts.Root, opts.DryRun)
	if err != nil {
		return err
	}

	line, err := writeConfig(opts.Root, opts.Login, opts.Repo, opts.DryRun)
	if err != nil {
		return err
	}
	if line != "" {
		done = append(done, line)
	}

	prefix := ""
	if opts.DryRun {
		prefix = "would: "
	}
	for _, l := range done {
		fmt.Println(prefix + l)
	}

	if opts.Scaffold {
		if err := initScaffold(opts); err != nil {
			return err
		}
	}
	if opts.MirrorHook {
		if err := initMirrorHook(opts); err != nil {
			return err
		}
	}
	return nil
}

// scaffoldOut is where the .claude/ tree goes for this run. An explicit
// --scaffold-out is used exactly as typed; without one it sits beside the
// marker, which is the only place another command can find it again.
func (o initOptions) scaffoldOut() string {
	if o.ScaffoldOut != "" {
		return o.ScaffoldOut
	}
	return filepath.Join(o.Root, scaffold.Marker)
}

func initScaffold(opts initOptions) error {
	out := opts.scaffoldOut()
	if err := genScaffold(out, opts.DryRun, false); err != nil {
		return err
	}
	if opts.DryRun {
		return nil
	}

	// The stamp is written last and is not load-bearing: nothing resolves from
	// it, and deleting it costs the warning in `kettle config` and nothing else.
	rec := &config.Scaffold{Version: Version, Out: relativeTo(opts.Root, out)}
	return config.SaveScaffoldFile(filepath.Join(opts.Root, project.Marker, "scaffold.yaml"), rec)
}

func initMirrorHook(opts initOptions) error {
	line, err := writeMirrorHook(opts.scaffoldOut(), opts.ForceSettings, opts.DryRun)
	if err != nil {
		// An existing settings.json is a decision for the operator, not a
		// failure of the run: everything before this point already happened and
		// saying otherwise would send them looking for damage there is none of.
		if errors.Is(err, errSettingsExist) {
			fmt.Fprintf(os.Stderr, "kettle init: the mirror hook was not registered — %v\n", err)
			return nil
		}
		return err
	}
	if line != "" {
		prefix := ""
		if opts.DryRun {
			prefix = "would: "
		}
		fmt.Println(prefix + line)
	}
	return nil
}

// relativeTo is path as written down in the scaffold record: relative when it
// sits under the project, absolute when the operator sent it somewhere else.
func relativeTo(root, path string) string {
	rel, err := filepath.Rel(root, path)
	if err != nil || strings.HasPrefix(rel, "..") {
		return path
	}
	return rel
}