// SPDX-FileCopyrightText: Amolith <amolith@secluded.site>
//
// SPDX-License-Identifier: AGPL-3.0-or-later

package task

import (
	"bufio"
	"errors"
	"fmt"
	"os"
	"strings"

	"git.secluded.site/go-lunatask"
	"git.secluded.site/lune/internal/client"
	"git.secluded.site/lune/internal/completion"
	"git.secluded.site/lune/internal/config"
	"git.secluded.site/lune/internal/dateutil"
	"git.secluded.site/lune/internal/ui"
	"git.secluded.site/lune/internal/validate"
	"github.com/spf13/cobra"
)

// ErrUnknownGoal indicates the specified goal key was not found in config.
var ErrUnknownGoal = errors.New("unknown goal key")

// ErrNoInput indicates no input was provided on stdin.
var ErrNoInput = errors.New("no input provided on stdin")

// AddCmd creates a new task. Exported for use by the add shortcut.
var AddCmd = &cobra.Command{
	Use:   "add NAME",
	Short: "Create a new task",
	Long: `Create a new task in Lunatask.

The task name is required. Use flags to set additional properties.
Use "-" as NAME to read the task name from stdin.`,
	Args: cobra.MinimumNArgs(1),
	RunE: runAdd,
}

func init() {
	AddCmd.Flags().StringP("area", "a", "", "Area key (from config)")
	AddCmd.Flags().StringP("goal", "g", "", "Goal key (from config)")
	AddCmd.Flags().StringP("status", "s", "", "Status: later, next, in-progress, waiting, completed")
	AddCmd.Flags().StringP("note", "n", "", "Task note (use - for stdin)")
	AddCmd.Flags().StringP("priority", "p", "", "Priority: lowest, low, normal, high, highest")
	AddCmd.Flags().IntP("estimate", "e", 0, "Estimate in minutes (0-720)")
	AddCmd.Flags().StringP("motivation", "m", "", "Motivation: must, should, want")
	AddCmd.Flags().Bool("important", false, "Mark as important (Eisenhower matrix)")
	AddCmd.Flags().Bool("not-important", false, "Mark as not important")
	AddCmd.Flags().Bool("urgent", false, "Mark as urgent (Eisenhower matrix)")
	AddCmd.Flags().Bool("not-urgent", false, "Mark as not urgent")
	AddCmd.Flags().String("schedule", "", "Schedule date (YYYY-MM-DD)")

	_ = AddCmd.RegisterFlagCompletionFunc("area", completion.Areas)
	_ = AddCmd.RegisterFlagCompletionFunc("goal", completion.Goals)
	_ = AddCmd.RegisterFlagCompletionFunc("status", completion.TaskStatuses)
	_ = AddCmd.RegisterFlagCompletionFunc("priority", completion.Priorities)
	_ = AddCmd.RegisterFlagCompletionFunc("motivation", completion.Motivations)
}

func runAdd(cmd *cobra.Command, args []string) error {
	name, err := resolveName(args[0])
	if err != nil {
		return err
	}

	apiClient, err := client.New()
	if err != nil {
		return err
	}

	builder := apiClient.NewTask(name)

	area, err := applyAreaAndGoal(cmd, builder)
	if err != nil {
		return err
	}

	if err := applyOptionalFlags(cmd, builder, area); err != nil {
		return err
	}

	task, err := ui.Spin("Creating task…", func() (*lunatask.Task, error) {
		return builder.Create(cmd.Context())
	})
	if err != nil {
		return err
	}

	fmt.Fprintln(cmd.OutOrStdout(), ui.Success.Render("Created task: "+task.ID))

	return nil
}

func resolveName(arg string) (string, error) {
	if arg != "-" {
		return arg, nil
	}

	scanner := bufio.NewScanner(os.Stdin)
	if scanner.Scan() {
		return strings.TrimSpace(scanner.Text()), nil
	}

	if err := scanner.Err(); err != nil {
		return "", fmt.Errorf("reading stdin: %w", err)
	}

	return "", ErrNoInput
}

//nolint:nilnil // nil area with no error is valid when area flag not provided
func applyAreaAndGoal(cmd *cobra.Command, builder *lunatask.TaskBuilder) (*config.Area, error) {
	areaKey, _ := cmd.Flags().GetString("area")
	goalKey, _ := cmd.Flags().GetString("goal")

	if areaKey == "" && goalKey == "" {
		return nil, nil
	}

	if areaKey == "" && goalKey != "" {
		fmt.Fprintln(cmd.ErrOrStderr(), ui.Warning.Render("Goal specified without area; ignoring"))

		return nil, nil
	}

	cfg, err := config.Load()
	if err != nil {
		return nil, err
	}

	area := cfg.AreaByKey(areaKey)
	if area == nil {
		return nil, fmt.Errorf("%w: %s", ErrUnknownArea, areaKey)
	}

	builder.InArea(area.ID)

	if goalKey == "" {
		return area, nil
	}

	goal := area.GoalByKey(goalKey)
	if goal == nil {
		return nil, fmt.Errorf("%w: %s", ErrUnknownGoal, goalKey)
	}

	builder.InGoal(goal.ID)

	return area, nil
}

//nolint:cyclop // flag handling inherently has many branches
func applyOptionalFlags(cmd *cobra.Command, builder *lunatask.TaskBuilder, area *config.Area) error {
	if status, _ := cmd.Flags().GetString("status"); status != "" {
		var (
			parsedStatus lunatask.TaskStatus
			err          error
		)

		if area != nil {
			parsedStatus, err = validate.TaskStatusForWorkflow(status, area.Workflow)
		} else {
			parsedStatus, err = validate.TaskStatus(status)
		}

		if err != nil {
			return err
		}

		builder.WithStatus(parsedStatus)
	}

	if note, _ := cmd.Flags().GetString("note"); note != "" {
		resolved, err := resolveNote(note)
		if err != nil {
			return err
		}

		builder.WithNote(resolved)
	}

	if priority, _ := cmd.Flags().GetString("priority"); priority != "" {
		p, err := lunatask.ParsePriority(priority)
		if err != nil {
			return err
		}

		builder.Priority(p)
	}

	if estimate, _ := cmd.Flags().GetInt("estimate"); estimate != 0 {
		builder.WithEstimate(estimate)
	}

	if motivation, _ := cmd.Flags().GetString("motivation"); motivation != "" {
		m, err := validate.Motivation(motivation)
		if err != nil {
			return err
		}

		builder.WithMotivation(m)
	}

	applyEisenhower(cmd, builder)

	return applySchedule(cmd, builder)
}

func applyEisenhower(cmd *cobra.Command, builder *lunatask.TaskBuilder) {
	if important, _ := cmd.Flags().GetBool("important"); important {
		builder.Important()
	} else if notImportant, _ := cmd.Flags().GetBool("not-important"); notImportant {
		builder.NotImportant()
	}

	if urgent, _ := cmd.Flags().GetBool("urgent"); urgent {
		builder.Urgent()
	} else if notUrgent, _ := cmd.Flags().GetBool("not-urgent"); notUrgent {
		builder.NotUrgent()
	}
}

func applySchedule(cmd *cobra.Command, builder *lunatask.TaskBuilder) error {
	schedule, _ := cmd.Flags().GetString("schedule")
	if schedule == "" {
		return nil
	}

	date, err := dateutil.Parse(schedule)
	if err != nil {
		return err
	}

	builder.ScheduledOn(date)

	return nil
}

func resolveNote(note string) (string, error) {
	if note != "-" {
		return note, nil
	}

	data, err := os.ReadFile("/dev/stdin")
	if err != nil {
		return "", fmt.Errorf("reading stdin: %w", err)
	}

	return strings.TrimSpace(string(data)), nil
}