package main

import (
	"os"
	"sort"
	"strconv"
	"strings"

	"github.com/spf13/cobra"
	intrgb "netdome.biz/paul/qmk-rgb/internal/rgb"
	"netdome.biz/paul/qmk-rgb/internal/via"
)

// Shell completion. The tool knows how to resolve a zone name and which profiles
// exist, and a shell only offers what the binary tells it about, so the binary has
// to say it. None of these open the keyboard: a shell asks while nothing is
// plugged in, and an error printed into a prompt is worse than an empty list.

// completeZoneNames offers the QMK subsystem names, which follow from the channel
// number and work on any board, plus the names the definition files give their
// channels, which are what a board calls them in VIA.
func completeZoneNames(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
	var names []string
	for _, ch := range via.LightingChannels {
		names = append(names, ch.Subsystem())
	}
	if defs, err := intrgb.LoadDefinitionsDir(definitionsPath()); err == nil {
		for _, def := range defs {
			for _, label := range def.Labels {
				names = append(names, label)
			}
		}
	}
	return narrow(names, toComplete), cobra.ShellCompDirectiveNoFileComp
}

// completeDeviceNumbers offers the keyboard numbers keyboard info prints, which
// come from enumeration and need no open keyboard.
func completeDeviceNumbers(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
	devices, err := discoverAll()
	if err != nil {
		return nil, cobra.ShellCompDirectiveNoFileComp
	}
	var numbers []string
	for _, d := range devices {
		numbers = append(numbers, strconv.Itoa(d.Index))
	}
	return narrow(numbers, toComplete), cobra.ShellCompDirectiveNoFileComp
}

// completeProfileNames offers the profiles in the directory, because load and
// delete take a name that is a file there.
func completeProfileNames(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
	entries, err := os.ReadDir(profilesPath())
	if err != nil {
		return nil, cobra.ShellCompDirectiveNoFileComp
	}
	var names []string
	for _, entry := range entries {
		if entry.IsDir() || !strings.HasSuffix(entry.Name(), ".json") {
			continue
		}
		names = append(names, strings.TrimSuffix(entry.Name(), ".json"))
	}
	return narrow(names, toComplete), cobra.ShellCompDirectiveNoFileComp
}

// narrow keeps the candidates a prefix matches, in order and without repeats: a
// completion list with duplicates reads as a bug, and one that ignores what has
// been typed makes the shell do the work it came here for.
func narrow(names []string, prefix string) []string {
	seen := make(map[string]bool, len(names))
	var out []string
	for _, name := range names {
		if prefix != "" && !strings.HasPrefix(name, prefix) {
			continue
		}
		if seen[name] {
			continue
		}
		seen[name] = true
		out = append(out, name)
	}
	sort.Strings(out)
	return out
}

// registerFlagCompletions teaches the shell what the persistent flags accept. The
// definition file is a path, so the shell completes paths for it on its own.
func registerFlagCompletions(root *cobra.Command) {
	_ = root.RegisterFlagCompletionFunc("zone", completeZoneNames)
	_ = root.RegisterFlagCompletionFunc("device", completeDeviceNumbers)
	_ = root.MarkFlagFilename("definition", "*.json")
}