package cli

import (
	"flag"
	"fmt"
	"os"
	"strings"

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

// convy add does two things at once, and they are one thing: it writes the
// subscription into the manifest and assembles the file. A subscription that
// left no file behind, or a file nothing subscribed to, is the state the model
// has no name for.

func runAdd(env Env, args []string) ExitCode {
	fs := flag.NewFlagSet("convy add", flag.ContinueOnError)
	fs.SetOutput(env.Err)
	root := fs.String("root", "", "root of the project; it is looked up upwards by default")
	forComponent := fs.String("for", "", "component to assemble for; needed when there is more than one")
	topicFlag := fs.String("topic", "", "topic to subscribe to; may also be given as the first argument")

	// The topic is taken off the front before the flags are parsed. The flag
	// package stops at the first argument that is not a flag, so "convy add
	// time --for backend" — the form the model writes — would otherwise lose
	// the component silently.
	topic := ""
	rest := args
	if len(rest) > 0 && !strings.HasPrefix(rest[0], "-") {
		topic, rest = rest[0], rest[1:]
	}
	if err := fs.Parse(rest); err != nil {
		return Usage
	}
	if *topicFlag != "" {
		if topic != "" && topic != *topicFlag {
			fmt.Fprintf(env.Err, "the topic is named twice and differently: %q and %q\n", topic, *topicFlag)
			return Usage
		}
		topic = *topicFlag
	}
	if rest := fs.Args(); len(rest) > 0 {
		if topic != "" && topic != rest[0] {
			fmt.Fprintf(env.Err, "the topic is named twice and differently: %q and %q\n", topic, rest[0])
			return Usage
		}
		topic = rest[0]
	}

	o, code := openProject(env, *root)
	if code != OK {
		return code
	}
	defer o.Close()

	if err := distinctDirs(o.Manifest); err != nil {
		fmt.Fprintln(env.Err, err)
		return Usage
	}

	name, c, code := componentOf(env, o.Manifest, *forComponent)
	if code != OK {
		return code
	}

	if topic == "" {
		if !env.Interactive {
			fmt.Fprintln(env.Err, "convy add without arguments asks which topic, and there is no terminal to ask on; name the topic as an argument")
			return Usage
		}
		answer, err := newDialogue(env).ask(topicField(o, c))
		if err != nil {
			fmt.Fprintln(env.Err, "\ninterrupted, nothing was written")
			return Usage
		}
		topic = answer
	}

	if !o.Suite.Manifest.TopicLive(topic) {
		if o.Suite.Manifest.TopicRetired(topic) {
			fmt.Fprintf(env.Err, "the suite has retired the topic %q: %s\n", topic, o.Suite.Manifest.Topics.Retired[topic])
			return Usage
		}
		fmt.Fprintf(env.Err, "the suite declares no topic %q; it declares: %s\n", topic, strings.Join(o.Suite.Manifest.LiveTopics(), ", "))
		return Usage
	}
	if c.Subscribed(topic) {
		fmt.Fprintf(env.Err, "the component %q is subscribed to %q already; convy pull reassembles it\n", name, topic)
		return Usage
	}

	made, err := project.Assemble(o.Suite, o.Root, c, topic)
	if err != nil {
		fmt.Fprintln(env.Err, err)
		return Failed
	}

	// The manifest is written after the file: a subscription recorded against
	// an assembly that failed would send the next pull looking for a copy that
	// was never made.
	source, err := os.ReadFile(o.Manifest.Path)
	if err != nil {
		fmt.Fprintln(env.Err, err)
		return Failed
	}
	updated, err := manifest.AddToList(source, "components."+name, "topics", topic)
	if err != nil {
		fmt.Fprintln(env.Err, err)
		return Failed
	}
	if err := os.WriteFile(o.Manifest.Path, updated, 0o644); err != nil {
		fmt.Fprintln(env.Err, err)
		return Failed
	}

	guide, err := project.Reading(o.LangRoot, o.Suite.Manifest.Language.Reading, o.Root, c.Dir)
	if err != nil {
		fmt.Fprintf(env.Err, "warning: %s\n", err)
	}

	fmt.Fprintf(env.Out, "\n%s → %s\n", topic, made.Path)
	for _, layer := range made.Layers {
		fmt.Fprintf(env.Out, "  %s\n", layer)
	}
	if guide != "" {
		fmt.Fprintf(env.Out, "\n%s refreshed\n", guide)
	}
	fmt.Fprintf(env.Out, "subscribed the component %q in %s\n", name, manifest.ProjectName)
	return OK
}

// topicField offers the topics the component has not taken yet.
func topicField(o *opened, c manifest.Component) Field {
	var free []string
	for _, t := range o.Suite.Manifest.LiveTopics() {
		if !c.Subscribed(t) {
			free = append(free, t)
		}
	}
	return Field{
		Flag:    "topic",
		Ask:     "Topic",
		Hint:    "A topic is taken whole: the file gathers every layer of it the component fits. " + describeTopics(o, free),
		Options: free,
		Check: func(v string) error {
			if !o.Suite.Manifest.TopicLive(v) {
				return fmt.Errorf("the suite declares no topic %q", v)
			}
			if c.Subscribed(v) {
				return fmt.Errorf("this component is subscribed to %q already", v)
			}
			return nil
		},
	}
}

func describeTopics(o *opened, free []string) string {
	if len(free) == 0 {
		return "The component is subscribed to everything the suite has."
	}
	parts := make([]string, 0, len(free))
	for _, t := range free {
		parts = append(parts, fmt.Sprintf("%s — %s", t, o.Suite.Manifest.Topics.Live[t]))
	}
	return "On offer: " + strings.Join(parts, "; ") + "."
}