package commandkit

import (
	"errors"
	"io"
	"strings"

	internalcobra "go.maximumdirect.net/commandkit/internal/cobra"
	commandmeta "go.maximumdirect.net/commandkit/internal/commandmeta"
)

func completeRequest(snapshot *routingSnapshot, words []string) (commandmeta.CompletionResult, error) {
	if len(words) == 0 {
		return commandmeta.CompletionResult{}, errors.New("completion request has no current word")
	}
	context := resolveCompletionContext(snapshot, words[:len(words)-1], words[len(words)-1])
	target := completionTargetFor(snapshot, context)
	result := commandmeta.CompletionResult{Prefix: target.prefix}
	switch target.kind {
	case completionTargetCommands, completionTargetFlags:
		result.Kind = commandmeta.CompletionChoices
		result.Choices = target.choices
	case completionTargetValue, completionTargetOperand:
		result.Kind = target.hint.Kind
		if target.hint.Kind == commandmeta.CompletionChoices {
			for _, choice := range target.hint.Choices {
				if strings.HasPrefix(choice.Value, target.valuePrefix) {
					result.Choices = append(result.Choices, choice)
				}
			}
		}
	}
	return result, nil
}

func (current *execution) complete(words []string) Outcome {
	result, err := completeRequest(current.snapshot, words)
	var reply string
	if err == nil {
		reply, err = internalcobra.CompletionReply(result)
	}
	if err != nil {
		reply = internalcobra.CompletionErrorReply()
	}
	_ = current.reporter.RenderOutput(func(writer io.Writer) error {
		_, writeErr := io.WriteString(writer, reply)
		return writeErr
	})
	if err != nil {
		return current.reporter.finalize(Failure("Could not complete the shell request.").WithCause(err), nil)
	}
	return current.reporter.finalize(Success(), nil)
}