package filedoc

import (
	"context"
	"encoding/json"
	"fmt"
	"strings"
	"time"

	"laodingbot/internal/logger"

	openai "github.com/openai/openai-go"
	"github.com/openai/openai-go/option"
	"github.com/openai/openai-go/shared"
)

type Config struct {
	APIKey  string
	BaseURL string
	Model   string
	Timeout time.Duration
}

type Tool struct {
	client         openai.Client
	model          string
	maxOutputChars int
	log            *logger.Logger
}

func New(cfg Config, maxOutputChars int, log *logger.Logger) *Tool {
	if strings.TrimSpace(cfg.Model) == "" {
		cfg.Model = "gpt-4o-mini"
	}
	if cfg.Timeout <= 0 {
		cfg.Timeout = 60 * time.Second
	}
	if maxOutputChars <= 0 {
		maxOutputChars = 12000
	}

	opts := []option.RequestOption{
		option.WithAPIKey(strings.TrimSpace(cfg.APIKey)),
		option.WithRequestTimeout(cfg.Timeout),
	}
	if strings.TrimSpace(cfg.BaseURL) != "" {
		opts = append(opts, option.WithBaseURL(strings.TrimSpace(cfg.BaseURL)))
	}

	return &Tool{
		client:         openai.NewClient(opts...),
		model:          cfg.Model,
		maxOutputChars: maxOutputChars,
		log:            log,
	}
}

func (t *Tool) Name() string { return "extract_file_document" }

func (t *Tool) Description() string {
	return "Extract full document details from a file ID via OpenAI. Input: file_id (supports plain ID, fileid://ID, or JSON {\"file_id\":\"...\"})."
}

func (t *Tool) Call(ctx context.Context, input string) (string, error) {
	fileID, userFocus, err := parseInput(input)
	if err != nil {
		return "", err
	}

	prompt := buildExtractionPrompt(fileID, userFocus)
	messages := []openai.ChatCompletionMessageParamUnion{
		openai.SystemMessage("fileid://" + fileID),
		openai.UserMessage([]openai.ChatCompletionContentPartUnionParam{
			openai.TextContentPart(prompt),
		}),
	}

	params := openai.ChatCompletionNewParams{
		Model:    shared.ChatModel(t.model),
		Messages: messages,
	}

	if t.log != nil {
		t.log.Infof("filedoc tool request model=%s file_id=%s", t.model, fileID)
	}

	resp, err := t.client.Chat.Completions.New(ctx, params)
	if err != nil {
		return "", fmt.Errorf("filedoc request failed: %w", err)
	}
	if len(resp.Choices) == 0 {
		return "", fmt.Errorf("filedoc returned empty choices")
	}

	out := strings.TrimSpace(resp.Choices[0].Message.Content)
	if out == "" {
		out = "未提取到可读的文档内容。请确认 file_id 是否有效以及模型是否支持文件解析。"
	}
	if len(out) > t.maxOutputChars {
		out = out[:t.maxOutputChars]
	}
	return out, nil
}

func buildExtractionPrompt(fileID, userFocus string) string {
	focus := strings.TrimSpace(userFocus)
	if focus == "" {
		focus = "请输出完整文档信息，包括标题、主题、核心观点、结构大纲、关键术语、重要结论、风险点与后续建议。"
	}

	return strings.Join([]string{
		"请基于所附文件输出完整文档信息。",
		"file_id: " + fileID,
		"",
		"输出要求：",
		"1) 文档基本信息：标题、文档类型、语言、可能作者/组织（若可判断）、时间线索（若可判断）。",
		"2) 结构化摘要：按章节或逻辑段落给出要点，尽量保持原文顺序。",
		"3) 关键数据与事实：列出关键数字、术语、专有名词、约束条件。",
		"4) 风险与不确定性：明确哪些信息来源于文档，哪些是无法确认。",
		"5) 面向执行的建议：给出可落地的后续行动项。",
		"",
		"补充关注点：",
		focus,
	}, "\n")
}

func parseInput(input string) (fileID string, userFocus string, err error) {
	raw := strings.TrimSpace(input)
	if raw == "" {
		return "", "", fmt.Errorf("empty input: expected file_id")
	}

	if strings.HasPrefix(raw, "{") {
		var payload map[string]any
		if jsonErr := json.Unmarshal([]byte(raw), &payload); jsonErr == nil {
			if id := firstNonEmptyString(payload, "file_id", "fileid", "id", "fileID"); id != "" {
				return normalizeFileID(id), firstNonEmptyString(payload, "focus", "query", "instruction", "prompt"), nil
			}
		}
	}

	lines := strings.Split(raw, "\n")
	for _, line := range lines {
		candidate := extractFileIDToken(line)
		if candidate != "" {
			focus := strings.TrimSpace(strings.ReplaceAll(raw, line, ""))
			return normalizeFileID(candidate), focus, nil
		}
	}

	candidate := extractFileIDToken(raw)
	if candidate == "" {
		return "", "", fmt.Errorf("no file_id found in input")
	}
	return normalizeFileID(candidate), "", nil
}

func extractFileIDToken(s string) string {
	fields := strings.FieldsFunc(s, func(r rune) bool {
		switch r {
		case ' ', '\t', '\n', '\r', ',', ';', '|':
			return true
		default:
			return false
		}
	})

	for _, f := range fields {
		tok := strings.TrimSpace(strings.Trim(f, "\"'()[]{}"))
		if tok == "" {
			continue
		}
		lower := strings.ToLower(tok)
		if strings.HasPrefix(lower, "fileid://") {
			return tok[len("fileid://"):]
		}
		if strings.HasPrefix(lower, "file_id=") || strings.HasPrefix(lower, "fileid=") {
			idx := strings.Index(tok, "=")
			if idx >= 0 && idx+1 < len(tok) {
				return tok[idx+1:]
			}
		}
		if strings.HasPrefix(lower, "file_") || strings.HasPrefix(lower, "file-") {
			return tok
		}
	}

	return ""
}

func normalizeFileID(id string) string {
	id = strings.TrimSpace(strings.Trim(id, "\"'"))
	if strings.HasPrefix(strings.ToLower(id), "fileid://") {
		return strings.TrimSpace(id[len("fileid://"):])
	}
	return id
}

func firstNonEmptyString(m map[string]any, keys ...string) string {
	for _, k := range keys {
		if v, ok := m[k]; ok {
			if s, ok := v.(string); ok && strings.TrimSpace(s) != "" {
				return strings.TrimSpace(s)
			}
		}
	}
	return ""
}