package main

import (
	"context"
	"encoding/json"
	"flag"
	"fmt"
	"os"
	"strconv"
	"strings"

	"git.knownelement.com/ukrrs/mopac-discourse-go"
)

func runCategories(ctx context.Context, c *discourse.Client, args []string) (any, error) {
	if len(args) == 0 {
		return nil, fmt.Errorf("categories needs a subcommand (list|create)")
	}
	switch args[0] {
	case "list":
		if len(args) != 1 {
			return nil, fmt.Errorf("categories list takes no arguments")
		}
		return c.ListCategories(ctx)
	case "create":
		fs := flag.NewFlagSet("categories create", flag.ContinueOnError)
		color := fs.String("color", "", "hex color, 6 digits")
		textColor := fs.String("text-color", "", "hex text color, 6 digits")
		perms := multiFlag{}
		fs.Var(&perms, "perm", "GROUP=LEVEL (1 reply/see, 2 create, 3 full); repeatable")
		if err := fs.Parse(flagsFirst(args[1:])); err != nil {
			return nil, err
		}
		if fs.NArg() != 1 {
			return nil, fmt.Errorf("categories create needs exactly one NAME")
		}
		req := discourse.CreateCategoryRequest{
			Name:      fs.Arg(0),
			Color:     *color,
			TextColor: *textColor,
		}
		for _, p := range perms {
			parts := strings.SplitN(p, "=", 2)
			if len(parts) != 2 {
				return nil, fmt.Errorf("-perm %q must be GROUP=LEVEL", p)
			}
			lvl, err := strconv.Atoi(parts[1])
			if err != nil || lvl < 1 || lvl > 3 {
				return nil, fmt.Errorf("-perm %q level must be 1, 2 or 3", p)
			}
			if req.Permissions == nil {
				req.Permissions = map[string]int{}
			}
			req.Permissions[parts[0]] = lvl
		}
		return c.CreateCategory(ctx, req)
	}
	return nil, fmt.Errorf("unknown categories subcommand %q", args[0])
}

func runTopics(ctx context.Context, c *discourse.Client, args []string) (any, error) {
	if len(args) == 0 {
		return nil, fmt.Errorf("topics needs a subcommand (list|show|create)")
	}
	switch args[0] {
	case "list":
		fs := flag.NewFlagSet("topics list", flag.ContinueOnError)
		catID := fs.Int("category", 0, "category id")
		slug := fs.String("slug", "", "category slug")
		latest := fs.Bool("latest", false, "instance-wide latest topics")
		if err := fs.Parse(args[1:]); err != nil {
			return nil, err
		}
		if *latest {
			return c.LatestTopics(ctx)
		}
		return c.ListTopics(ctx, *catID, *slug)
	case "show":
		if len(args) != 2 {
			return nil, fmt.Errorf("topics show needs exactly one ID")
		}
		id, err := strconv.Atoi(args[1])
		if err != nil {
			return nil, fmt.Errorf("topic id %q is not a number", args[1])
		}
		return c.GetTopic(ctx, id)
	case "create":
		fs := flag.NewFlagSet("topics create", flag.ContinueOnError)
		title := fs.String("title", "", "topic title (required)")
		category := fs.Int("category", 0, "category id (required)")
		raw := fs.String("raw", "", "markdown body inline")
		file := fs.String("file", "", "markdown body from file (overrides -raw)")
		if err := fs.Parse(flagsFirst(args[1:])); err != nil {
			return nil, err
		}
		body, err := bodyFrom(*file, *raw)
		if err != nil {
			return nil, err
		}
		return c.CreateTopic(ctx, discourse.CreateTopicRequest{Title: *title, Raw: body, Category: *category})
	}
	return nil, fmt.Errorf("unknown topics subcommand %q", args[0])
}

func runPosts(ctx context.Context, c *discourse.Client, args []string) (any, error) {
	if len(args) == 0 {
		return nil, fmt.Errorf("posts needs a subcommand (create|update)")
	}
	switch args[0] {
	case "create":
		fs := flag.NewFlagSet("posts create", flag.ContinueOnError)
		topic := fs.Int("topic", 0, "topic id (required)")
		raw := fs.String("raw", "", "markdown body inline")
		file := fs.String("file", "", "markdown body from file (overrides -raw)")
		if err := fs.Parse(flagsFirst(args[1:])); err != nil {
			return nil, err
		}
		body, err := bodyFrom(*file, *raw)
		if err != nil {
			return nil, err
		}
		return c.CreatePost(ctx, discourse.CreatePostRequest{TopicID: *topic, Raw: body})
	case "update":
		fs := flag.NewFlagSet("posts update", flag.ContinueOnError)
		raw := fs.String("raw", "", "markdown body inline")
		file := fs.String("file", "", "markdown body from file (overrides -raw)")
		reason := fs.String("reason", "", "edit reason")
		if err := fs.Parse(flagsFirst(args[1:])); err != nil {
			return nil, err
		}
		if fs.NArg() != 1 {
			return nil, fmt.Errorf("posts update needs exactly one ID")
		}
		id, err := strconv.Atoi(fs.Arg(0))
		if err != nil {
			return nil, fmt.Errorf("post id %q is not a number", fs.Arg(0))
		}
		body, err := bodyFrom(*file, *raw)
		if err != nil {
			return nil, err
		}
		return c.UpdatePost(ctx, id, body, *reason)
	}
	return nil, fmt.Errorf("unknown posts subcommand %q", args[0])
}

func runRaw(ctx context.Context, c *discourse.Client, args []string) (any, error) {
	if len(args) < 2 {
		return nil, fmt.Errorf("raw needs METHOD and PATH")
	}
	method := strings.ToUpper(args[0])
	path := args[1]
	fs := flag.NewFlagSet("raw", flag.ContinueOnError)
	data := fs.String("data", "", "JSON body inline or @file")
	if err := fs.Parse(args[2:]); err != nil {
		return nil, err
	}
	var body any
	if *data != "" {
		raw := []byte(*data)
		if strings.HasPrefix(*data, "@") {
			b, err := os.ReadFile(strings.TrimPrefix(*data, "@"))
			if err != nil {
				return nil, err
			}
			raw = b
		}
		if err := json.Unmarshal(raw, &body); err != nil {
			return nil, fmt.Errorf("-data is not valid JSON: %v", err)
		}
	}
	var out any
	if err := c.Do(ctx, method, path, body, &out); err != nil {
		return nil, err
	}
	return out, nil
}

func bodyFrom(file, raw string) (string, error) {
	if file != "" {
		b, err := os.ReadFile(file)
		if err != nil {
			return "", err
		}
		return string(b), nil
	}
	if raw == "" {
		return "", fmt.Errorf("body required: -raw TEXT or -file PATH")
	}
	return raw, nil
}

// flagsFirst lets flags appear after positional args ("create NAME -color
// X"): every flag here takes a value, so tokens starting with "-" grab
// their neighbor; the rest are positional. Reordered as flags-then-
// positionals for flag.Parse.
func flagsFirst(args []string) []string {
	var flags, pos []string
	for i := 0; i < len(args); i++ {
		if strings.HasPrefix(args[i], "-") && args[i] != "-" {
			flags = append(flags, args[i])
			if i+1 < len(args) {
				i++
				flags = append(flags, args[i])
			}
		} else {
			pos = append(pos, args[i])
		}
	}
	return append(flags, pos...)
}

// multiFlag collects repeatable string flags (-perm a=1 -perm b=2).
type multiFlag []string

func (m *multiFlag) String() string { return strings.Join(*m, ",") }
func (m *multiFlag) Set(v string) error {
	*m = append(*m, v)
	return nil
}