package io

import (
	"context"
	"fmt"
	"log/slog"
	"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
	// renderer 是「浏览器渲染取正文」这一档（design/28 §1 M5 / §8 B5）。
	// nil = 关着（默认，见 WithBrowserFallback）。
	renderer BodyRenderer
}

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

// 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.
//
// 取正文走**降级链**（design/28 §1 M5 / §8 B5）：直连 fetch →（失败 / 判定为动态页）
// ⇒ 浏览器渲染。结果里的 `fetchedBy` 是**如实标注**（direct / browser）；两条档的
// 失败原文各自留在 directError / browserError 里，绝不静默替换、绝不掩盖。
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")
	}
	max := w.maxBytes
	if v, ok := argInt(m, "max_bytes"); ok && v > 0 {
		max = int64(v)
	}
	body, err := w.fetchBody(ctx, rawURL, max)
	if err != nil {
		return nil, err
	}
	out := map[string]any{
		"url":          rawURL,
		"content_type": body.contentType,
		"text":         body.text,
		"truncated":    body.truncated,
		// fetchedBy：正文**实际**来自哪条路。它是 M5 的硬要求（不许静默替换）——
		// 见到 browser 就意味着直连失败过、或被判成了动态页。
		"fetchedBy": body.fetchedBy,
	}
	// 以下字段只在**确有其事**时出现（有内容的失败/来源才写，不塞空串）。
	if body.directError != "" {
		out["directError"] = body.directError
	}
	if body.browserSource != "" {
		out["browserSource"] = body.browserSource
	}
	if body.browserError != "" {
		out["browserError"] = body.browserError
	}
	if body.dynamicSuspect {
		out["dynamicSuspect"] = true
	}
	return out, nil
}