package cmd

import (
	"fmt"
	"io"
	"os"

	"github.com/zk-org/zk/internal/cli"
	"github.com/zk-org/zk/internal/core"
	"github.com/zk-org/zk/internal/util/errors"
	"github.com/zk-org/zk/internal/util/strings"
)

// Tag manages the note tags in the notebook.
type Tag struct {
	List TagList `cmd group:"cmd" default:"withargs" help:"List all the note tags."`
}

// TagList lists all the note tags.
type TagList struct {
	Format     string   `group:format short:f placeholder:TEMPLATE   help:"Pretty print the list using a custom template or one of the predefined formats: name, full, json, jsonl."`
	Header     string   `group:format                                help:"Arbitrary text printed at the start of the list."`
	Footer     string   `group:format default:\n                     help:"Arbitrary text printed at the end of the list."`
	Delimiter  string   "group:format short:d default:\n             help:\"Print tags delimited by the given separator.\""
	Delimiter0 bool     "group:format short:0 name:delimiter0        help:\"Print tags delimited by ASCII NUL characters. This is useful when used in conjunction with `xargs -0`.\""
	NoPager    bool     `group:format short:P help:"Do not pipe output into a pager."`
	Quiet      bool     `group:format short:q help:"Do not print the total number of tags found."`
	Sort       []string `group:sort short:s placeholder:TERM help:"Order the tags by the given criterion."`
}

func (cmd *TagList) Run(container *cli.Container) error {
	cmd.Header = strings.ExpandWhitespaceLiterals(cmd.Header)
	cmd.Footer = strings.ExpandWhitespaceLiterals(cmd.Footer)
	cmd.Delimiter = strings.ExpandWhitespaceLiterals(cmd.Delimiter)

	if cmd.Delimiter0 {
		if cmd.Delimiter != "\n" {
			return errors.New("--delimiter and --delimiter0 can't be used together")
		}
		if cmd.Header != "" {
			return errors.New("--footer and --delimiter0 can't be used together")
		}
		if cmd.Footer != "\n" {
			return errors.New("--footer and --delimiter0 can't be used together")
		}

		cmd.Delimiter = "\x00"
		cmd.Footer = "\x00"
	}

	if cmd.Format == "json" || cmd.Format == "jsonl" {
		if cmd.Header != "" {
			return errors.New("--header can't be used with JSON format")
		}
		if cmd.Footer != "\n" {
			return errors.New("--footer can't be used with JSON format")
		}
		if cmd.Delimiter != "\n" {
			return errors.New("--delimiter can't be used with JSON format")
		}

		switch cmd.Format {
		case "json":
			cmd.Delimiter = ","
			cmd.Header = "["
			cmd.Footer = "]\n"

		case "jsonl":
			// > The last character in the file may be a line separator, and it
			// > will be treated the same as if there was no line separator
			// > present.
			// > https://jsonlines.org/
			cmd.Footer = "\n"
		}
	}

	notebook, err := container.CurrentNotebook()
	if err != nil {
		return err
	}

	format, err := notebook.NewCollectionFormatter(cmd.tagTemplate())
	if err != nil {
		return err
	}

	sorters, err := core.CollectionSortersFromStrings(cmd.Sort)
	if err != nil {
		return err
	}

	tags, err := notebook.FindCollections(core.CollectionKindTag, sorters)
	if err != nil {
		return err
	}

	count := len(tags)
	if count > 0 {
		err = container.Paginate(cmd.NoPager, func(out io.Writer) error {
			if cmd.Header != "" {
				fmt.Fprint(out, cmd.Header)
			}
			for i, tag := range tags {
				if i > 0 {
					fmt.Fprint(out, cmd.Delimiter)
				}

				ft, err := format(tag)
				if err != nil {
					return err
				}
				fmt.Fprint(out, ft)
			}
			if cmd.Footer != "" {
				fmt.Fprint(out, cmd.Footer)
			}

			return nil
		})
	}

	if err == nil && !cmd.Quiet {
		fmt.Fprintf(os.Stderr, "\nFound %d %s\n", count, strings.Pluralize("tag", count))
	}

	return err
}

func (cmd *TagList) tagTemplate() string {
	format := cmd.Format
	if format == "" {
		format = "full"
	}

	templ, ok := defaultTagFormats[format]
	if !ok {
		templ = strings.ExpandWhitespaceLiterals(format)
	}

	return templ
}

var defaultTagFormats = map[string]string{
	"json":  `{{json .}}`,
	"jsonl": `{{json .}}`,
	"name":  `{{name}}`,
	"full":  `{{name}} ({{note-count}})`,
}