package cmd

import (
	"fmt"
	"strings"

	"git.jnss.me/joakim/opal/internal/engine"
	"github.com/spf13/cobra"
)

// taskFilterCompletion provides dynamic completions for task filter arguments.
// Suggests +tag, project:name, and attribute value completions from the database.
func taskFilterCompletion(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
	// If typing a key:value, complete the value part
	if idx := strings.IndexByte(toComplete, ':'); idx >= 0 {
		key := toComplete[:idx]
		if engine.ValidAttributeKeys[key] {
			return attributeValueCompletions(key, toComplete), cobra.ShellCompDirectiveNoFileComp
		}
	}

	// If toComplete is a prefix of an attribute key, return only key:
	// completions with NoSpace so the cursor stays after the colon.
	if toComplete != "" && !strings.HasPrefix(toComplete, "+") && !strings.HasPrefix(toComplete, "-") {
		var keyCompletions []string
		for key := range engine.ValidAttributeKeys {
			if strings.HasPrefix(key, toComplete) {
				keyCompletions = append(keyCompletions, fmt.Sprintf("%s:", key))
			}
		}
		if len(keyCompletions) > 0 {
			return keyCompletions, cobra.ShellCompDirectiveNoFileComp | cobra.ShellCompDirectiveNoSpace
		}
	}

	var completions []string

	tags, err := engine.GetAllTags()
	if err == nil {
		for _, tag := range tags {
			completions = append(completions, fmt.Sprintf("+%s", tag))
		}
	}

	projects, err := engine.GetAllProjects()
	if err == nil {
		for _, proj := range projects {
			completions = append(completions, fmt.Sprintf("project:%s", proj))
		}
	}

	// Add known attribute keys
	for key := range engine.ValidAttributeKeys {
		completions = append(completions, fmt.Sprintf("%s:", key))
	}

	return completions, cobra.ShellCompDirectiveNoFileComp | cobra.ShellCompDirectiveNoSpace
}

// attributeValueCompletions returns key:value completions for a known attribute key.
// Cobra filters by prefix automatically, so we return all values prefixed with "key:".
func attributeValueCompletions(key, toComplete string) []string {
	var values []string

	switch key {
	case "status":
		values = []string{"pending", "completed", "deleted", "recurring"}
	case "priority":
		values = []string{"H", "M", "L"}
	case "project":
		projects, err := engine.GetAllProjects()
		if err == nil {
			values = projects
		}
	case "due", "wait", "scheduled", "until":
		values = []string{
			"today", "tomorrow", "yesterday", "now",
			"eod", "sow", "eow", "som", "eom",
			"mon", "tue", "wed", "thu", "fri", "sat", "sun",
		}
	case "recur":
		values = []string{"daily", "weekly", "monthly", "yearly", "1d", "1w", "2w", "1m", "1y"}
	}

	completions := make([]string, 0, len(values))
	for _, v := range values {
		completions = append(completions, fmt.Sprintf("%s:%s", key, v))
	}
	return completions
}

// rootValidArgsFunction provides completions for root-level arguments,
// enabling flexible syntax like "opal 1 de<TAB>" to complete to "delete".
func rootValidArgsFunction(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
	// Delegate to taskFilterCompletion first — if toComplete is a partial
	// attribute key, it returns early with NoSpace and we should honour that.
	filterCompletions, directive := taskFilterCompletion(cmd, args, toComplete)

	var completions []string

	// Suggest command names
	for _, name := range commandNames {
		completions = append(completions, name)
	}

	// Suggest report names
	for _, name := range reportNames {
		completions = append(completions, name)
	}

	completions = append(completions, filterCompletions...)

	return completions, directive
}

func init() {
	// Root command completions for flexible syntax (e.g., "opal 1 de<TAB>")
	rootCmd.ValidArgsFunction = rootValidArgsFunction

	// Register dynamic completions for commands that accept filters
	addCmd.ValidArgsFunction = taskFilterCompletion
	doneCmd.ValidArgsFunction = taskFilterCompletion
	deleteCmd.ValidArgsFunction = taskFilterCompletion
	modifyCmd.ValidArgsFunction = taskFilterCompletion
	startCmd.ValidArgsFunction = taskFilterCompletion
	stopCmd.ValidArgsFunction = taskFilterCompletion
	editCmd.ValidArgsFunction = taskFilterCompletion
	infoCmd.ValidArgsFunction = taskFilterCompletion
	annotateCmd.ValidArgsFunction = taskFilterCompletion
	denotateCmd.ValidArgsFunction = taskFilterCompletion
	logCmd.ValidArgsFunction = taskFilterCompletion
}