package main

import (
	"context"
	"fmt"
	"io"
	"net/http"
	"os/exec"
	"runtime"
	"strings"

	"github.com/urfave/cli/v3"
)

var nip = &cli.Command{
	Name:  "nip",
	Usage: "get the description of a NIP from its number",
	Description: `fetches the NIPs README from GitHub and parses it to find the description of the given NIP number.
	
example:
	nak nip 1
	nak nip list
	nak nip open 1`,
	ArgsUsage: "<NIP number>",
	Commands: []*cli.Command{
		{
			Name:  "list",
			Usage: "list all NIPs",
			Action: func(ctx context.Context, c *cli.Command) error {
				return iterateNips(func(nip, desc, link string) bool {
					stdout(nip + ": " + desc)
					return true
				})
			},
		},
		{
			Name:  "open",
			Usage: "open the NIP page in the browser",
			Action: func(ctx context.Context, c *cli.Command) error {
				reqNum := c.Args().First()
				if reqNum == "" {
					return fmt.Errorf("missing NIP number")
				}

				normalize := func(s string) string {
					s = strings.ToLower(s)
					s = strings.TrimPrefix(s, "nip-")
					s = strings.TrimLeft(s, "0")
					if s == "" {
						s = "0"
					}
					return s
				}

				reqNum = normalize(reqNum)

				foundLink := ""
				err := iterateNips(func(nip, desc, link string) bool {
					nipNum := normalize(nip)
					if nipNum == reqNum {
						foundLink = link
						return false
					}
					return true
				})

				if err != nil {
					return err
				}

				if foundLink == "" {
					return fmt.Errorf("NIP-%s not found", strings.ToUpper(reqNum))
				}

				url := "https://github.com/nostr-protocol/nips/blob/master/" + foundLink
				fmt.Println("Opening " + url)

				var cmd *exec.Cmd
				switch runtime.GOOS {
				case "darwin":
					cmd = exec.Command("open", url)
				case "windows":
					cmd = exec.Command("cmd", "/c", "start", url)
				default:
					cmd = exec.Command("xdg-open", url)
				}

				return cmd.Start()
			},
		},
	},
	Action: func(ctx context.Context, c *cli.Command) error {
		reqNum := c.Args().First()
		if reqNum == "" {
			return fmt.Errorf("missing NIP number")
		}

		normalize := func(s string) string {
			s = strings.ToLower(s)
			s = strings.TrimPrefix(s, "nip-")
			s = strings.TrimLeft(s, "0")
			if s == "" {
				s = "0"
			}
			return s
		}

		reqNum = normalize(reqNum)

		found := false
		err := iterateNips(func(nip, desc, link string) bool {
			nipNum := normalize(nip)

			if nipNum == reqNum {
				stdout(strings.TrimSpace(desc))
				found = true
				return false
			}
			return true
		})

		if err != nil {
			return err
		}

		if !found {
			return fmt.Errorf("NIP-%s not found", strings.ToUpper(reqNum))
		}
		return nil
	},
}

func iterateNips(yield func(nip, desc, link string) bool) error {
	resp, err := http.Get("https://raw.githubusercontent.com/nostr-protocol/nips/master/README.md")
	if err != nil {
		return fmt.Errorf("failed to fetch NIPs README: %w", err)
	}
	defer resp.Body.Close()

	body, err := io.ReadAll(resp.Body)
	if err != nil {
		return fmt.Errorf("failed to read NIPs README: %w", err)
	}
	bodyStr := string(body)
	epoch := strings.Index(bodyStr, "## List")

	lines := strings.SplitSeq(bodyStr[epoch+8:], "\n")
	for line := range lines {
		line = strings.TrimSpace(line)
		if strings.HasPrefix(line, "##") {
			break
		}
		if !strings.HasPrefix(line, "- [NIP-") {
			continue
		}

		start := strings.Index(line, "[")
		end := strings.Index(line, "]")
		if start == -1 || end == -1 || end < start {
			continue
		}

		content := line[start+1 : end]

		parts := strings.SplitN(content, ":", 2)
		if len(parts) != 2 {
			continue
		}

		nipPart := parts[0]
		descPart := parts[1]

		rest := line[end+1:]
		linkStart := strings.Index(rest, "(")
		linkEnd := strings.Index(rest, ")")
		link := ""
		if linkStart != -1 && linkEnd != -1 && linkEnd > linkStart {
			link = rest[linkStart+1 : linkEnd]
		}

		if !yield(nipPart, strings.TrimSpace(descPart), link) {
			break
		}
	}
	return nil
}