package io

import (
	"context"
	"fmt"
	"log/slog"
	"mime"
	"net/http"
	"strings"

	"git.yeij.top/AskaEth/Cyrene_v2/pkg/plugins/sdk"
)

// Compile-time assertion that webFetchTool implements sdk.Tool.
var _ sdk.Tool = (*webFetchTool)(nil)

// webFetchTool fetches a URL over HTTP and returns its readable text, limited by
// size and content type, extracting text from HTML when appropriate.
type webFetchTool struct {
	client       *http.Client
	allowedHosts []string
	maxBytes     int64
	log          *slog.Logger
}

func newWebFetchTool(t *tools) *webFetchTool {
	return &webFetchTool{
		client:       t.client,
		allowedHosts: t.allowedHosts,
		maxBytes:     t.maxFetchBytes,
		log:          t.log,
	}
}

// Name implements sdk.Tool.
func (w *webFetchTool) Name() string { return "web-fetch" }

// Description implements sdk.Tool.
func (w *webFetchTool) Description() string {
	return "Fetch a URL and return its readable text, limited by size and content type."
}

// Parameters implements sdk.Tool.
func (w *webFetchTool) Parameters() (map[string]any, error) {
	return map[string]any{
		"type": "object",
		"properties": map[string]any{
			"url":       map[string]any{"type": "string", "description": "Absolute http(s) URL."},
			"max_bytes": map[string]any{"type": "integer", "description": "Response size cap in bytes."},
		},
		"required": []any{"url"},
	}, nil
}

// Execute implements sdk.Tool.
func (w *webFetchTool) Execute(ctx context.Context, args any) (any, error) {
	m, ok := args.(map[string]any)
	if !ok {
		return nil, fmt.Errorf("io: web-fetch: args must be an object")
	}
	rawURL := argString(m, "url")
	if strings.TrimSpace(rawURL) == "" {
		return nil, fmt.Errorf("io: web-fetch: url is required")
	}
	if _, err := validateRequestURL(ctx, rawURL, w.allowedHosts); err != nil {
		return nil, err
	}
	if w.client == nil {
		return nil, fmt.Errorf("io: web-fetch: no underlying client")
	}
	req, err := http.NewRequestWithContext(ctx, http.MethodGet, rawURL, nil)
	if err != nil {
		return nil, fmt.Errorf("io: web-fetch: build request: %w", err)
	}
	resp, err := w.client.Do(req)
	if err != nil {
		return nil, fmt.Errorf("io: web-fetch: do: %w", err)
	}
	defer resp.Body.Close()
	if resp.StatusCode != http.StatusOK {
		return nil, fmt.Errorf("io: web-fetch: url returned status %d", resp.StatusCode)
	}
	mt := "text/plain"
	if rawCT := resp.Header.Get("Content-Type"); rawCT != "" {
		var err error
		mt, _, err = mime.ParseMediaType(rawCT)
		if err != nil || !isTextContentType(mt) {
			return nil, fmt.Errorf("io: web-fetch: unexpected content type %q", rawCT)
		}
	}
	max := w.maxBytes
	if v, ok := argInt(m, "max_bytes"); ok && v > 0 {
		max = int64(v)
	}
	data, truncated, err := readLimited(resp.Body, max)
	if err != nil {
		return nil, fmt.Errorf("io: web-fetch: read: %w", err)
	}
	text := string(data)
	if isHTML(mt) {
		text = htmlToText(text)
	}
	return map[string]any{
		"url":          rawURL,
		"content_type": mt,
		"text":         text,
		"truncated":    truncated,
	}, nil
}