"""OCR 单据字段提取器单元测试。

覆盖:
  - OcrTextElement / ExtractedField / ExtractionResult 数据结构
  - 四种提取策略的独立测试
  - 坐标计算正确性
  - 边界情况（空元素、无匹配、部分匹配）
"""

import sys
import os
import math
from pathlib import Path

sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))

import pytest

from backend.ocr_extractor import (
    OcrTextElement,
    ExtractedField,
    ExtractionResult,
    OcrExtractor,
    extract_ocr_fields,
    extract_from_layout,
)


class TestOcrTextElement:
    """测试 OcrTextElement 数据类。"""

    def test_bbox_property(self):
        elem = OcrTextElement(
            text="发票代码",
            x_min=100.0,
            y_min=50.0,
            x_max=250.0,
            y_max=80.0,
        )
        assert elem.bbox == [100.0, 50.0, 250.0, 80.0]

    def test_center_coordinates(self):
        elem = OcrTextElement(
            text="测试",
            x_min=100.0,
            y_min=50.0,
            x_max=200.0,
            y_max=100.0,
        )
        assert elem.center_x == 150.0
        assert elem.center_y == 75.0

    def test_width_height(self):
        elem = OcrTextElement(
            text="测试",
            x_min=10.0,
            y_min=20.0,
            x_max=100.0,
            y_max=70.0,
        )
        assert elem.width == 90.0
        assert elem.height == 50.0

    def test_default_confidence(self):
        elem = OcrTextElement(
            text="测试",
            x_min=0,
            y_min=0,
            x_max=10,
            y_max=10,
        )
        assert elem.confidence == 1.0


class TestExtractedField:
    """测试 ExtractedField 数据类。"""

    def test_field_creation(self):
        field = ExtractedField(
            field_name="发票代码",
            field_value="1234567890",
            bbox=[100, 50, 200, 80],
            confidence=0.95,
            extraction_method="exact_match",
        )
        assert field.field_name == "发票代码"
        assert field.field_value == "1234567890"
        assert field.bbox == [100, 50, 200, 80]
        assert field.confidence == 0.95
        assert field.extraction_method == "exact_match"


class TestExtractionResult:
    """测试 ExtractionResult 数据类。"""

    def test_to_dict_basic(self):
        result = ExtractionResult(
            file_path="/test/invoice.png",
            image_size=(800, 600),
            ocr_available=True,
        )
        d = result.to_dict()
        assert d["file_path"] == "/test/invoice.png"
        assert d["image_size"] == (800, 600)
        assert d["ocr_available"] is True
        assert d["fields"] == []
        assert d["total_elements"] == 0
        assert d["errors"] == []

    def test_to_dict_with_fields(self):
        result = ExtractionResult(
            file_path="/test/invoice.png",
            image_size=(800, 600),
            ocr_available=True,
        )
        result.fields.append(
            ExtractedField(
                field_name="发票代码",
                field_value="1234567890",
                bbox=[100, 50, 200, 80],
                confidence=0.95,
                extraction_method="exact_match",
            )
        )
        d = result.to_dict()
        assert len(d["fields"]) == 1
        assert d["fields"][0]["field_name"] == "发票代码"
        assert d["fields"][0]["field_value"] == "1234567890"
        assert d["fields"][0]["bbox"] == [100, 50, 200, 80]
        assert d["fields"][0]["confidence"] == 0.95
        assert d["fields"][0]["extraction_method"] == "exact_match"

    def test_to_dict_with_error(self):
        result = ExtractionResult(
            file_path="/test/missing.png",
            image_size=(0, 0),
            errors=["文件不存在: /test/missing.png"],
        )
        d = result.to_dict()
        assert d["errors"] == ["文件不存在: /test/missing.png"]


class TestElementGrouping:
    """测试元素行分组功能。"""

    def test_group_single_row(self):
        elements = [
            OcrTextElement("A", 10, 50, 50, 70),
            OcrTextElement("B", 60, 50, 110, 70),
            OcrTextElement("C", 120, 50, 170, 70),
        ]
        rows = OcrExtractor._group_elements_by_rows(elements)
        assert len(rows) == 1
        assert len(rows[0]) == 3

    def test_group_multiple_rows(self):
        elements = [
            OcrTextElement("A1", 10, 50, 50, 70),
            OcrTextElement("B1", 60, 50, 110, 70),
            OcrTextElement("A2", 10, 120, 50, 140),
            OcrTextElement("B2", 60, 120, 110, 140),
            OcrTextElement("A3", 10, 200, 50, 220),
        ]
        rows = OcrExtractor._group_elements_by_rows(elements)
        assert len(rows) == 3
        assert len(rows[0]) == 2
        assert len(rows[1]) == 2
        assert len(rows[2]) == 1

    def test_group_empty(self):
        rows = OcrExtractor._group_elements_by_rows([])
        assert rows == []

    def test_group_single_element(self):
        rows = OcrExtractor._group_elements_by_rows([
            OcrTextElement("X", 10, 50, 50, 70)
        ])
        assert len(rows) == 1
        assert len(rows[0]) == 1


class TestTextSimilarity:
    """测试文本相似度计算。"""

    def test_exact_match(self):
        sim = OcrExtractor._text_similarity("发票代码", "发票代码")
        assert sim == 1.0

    def test_partial_match(self):
        sim = OcrExtractor._text_similarity("发票代码", "代码")
        assert sim > 0.5

    def test_no_match(self):
        sim = OcrExtractor._text_similarity("发票代码", "xyz")
        assert sim == 0.0

    def test_empty_strings(self):
        assert OcrExtractor._text_similarity("", "abc") == 0.0
        assert OcrExtractor._text_similarity("abc", "") == 0.0
        assert OcrExtractor._text_similarity("", "") == 0.0

    def test_substring_match(self):
        sim = OcrExtractor._text_similarity("代码", "发票代码")
        assert sim > 0.7


class TestExactKVMatch:
    """测试策略1: 精确键值对匹配。"""

    def test_colon_separator(self):
        extractor = OcrExtractor()
        elements = [
            OcrTextElement("发票代码: 1234567890", 50, 50, 300, 80),
        ]
        result = extractor._exact_kv_match("发票代码", elements)
        assert result is not None
        assert result.field_value == "1234567890"
        assert result.confidence == 0.95

    def test_chinese_colon(self):
        extractor = OcrExtractor()
        elements = [
            OcrTextElement("发票号码：87654321", 50, 50, 300, 80),
        ]
        result = extractor._exact_kv_match("发票号码", elements)
        assert result is not None
        assert result.field_value == "87654321"

    def test_space_separator(self):
        extractor = OcrExtractor()
        elements = [
            OcrTextElement("合计金额 999.00", 50, 50, 300, 80),
        ]
        result = extractor._exact_kv_match("合计金额", elements)
        assert result is not None
        assert result.field_value == "999.00"

    def test_equals_separator(self):
        extractor = OcrExtractor()
        elements = [
            OcrTextElement("数量=5", 50, 50, 200, 80),
        ]
        result = extractor._exact_kv_match("数量", elements)
        assert result is not None
        assert result.field_value == "5"

    def test_field_not_found(self):
        extractor = OcrExtractor()
        elements = [
            OcrTextElement("其他内容: 123", 50, 50, 200, 80),
        ]
        result = extractor._exact_kv_match("发票代码", elements)
        assert result is None


class TestFuzzyKVMatch:
    """测试策略2: 模糊键值对匹配。"""

    def test_adjacent_same_row(self):
        extractor = OcrExtractor()
        elements = [
            OcrTextElement("发票代码", 50, 50, 150, 80),
            OcrTextElement("1234567890", 200, 50, 350, 80),
        ]
        result = extractor._fuzzy_kv_match("发票代码", elements)
        assert result is not None
        assert result.field_value == "1234567890"
        assert result.confidence == 0.75

    def test_adjacent_next_row(self):
        extractor = OcrExtractor()
        elements = [
            OcrTextElement("发票代码", 50, 50, 150, 80),
            OcrTextElement("1234567890", 50, 100, 200, 130),
        ]
        result = extractor._fuzzy_kv_match("发票代码", elements)
        assert result is not None
        assert result.field_value == "1234567890"

    def test_field_name_not_found(self):
        extractor = OcrExtractor()
        elements = [
            OcrTextElement("其他信息", 50, 50, 150, 80),
            OcrTextElement("1234567890", 200, 50, 350, 80),
        ]
        result = extractor._fuzzy_kv_match("发票代码", elements)
        assert result is None


class TestRegexMatch:
    """测试策略3: 正则模式匹配。"""

    def test_invoice_code_pattern(self):
        extractor = OcrExtractor()
        elements = [
            OcrTextElement("1234567890", 100, 50, 250, 80),
        ]
        result = extractor._regex_match("发票代码", elements)
        assert result is not None
        assert result.field_value == "1234567890"

    def test_invoice_number_pattern(self):
        extractor = OcrExtractor()
        elements = [
            OcrTextElement("87654321", 100, 50, 200, 80),
        ]
        result = extractor._regex_match("发票号码", elements)
        assert result is not None
        assert result.field_value == "87654321"

    def test_amount_pattern(self):
        extractor = OcrExtractor()
        elements = [
            OcrTextElement("1,234.56", 100, 50, 200, 80),
        ]
        result = extractor._regex_match("合计金额", elements)
        assert result is not None
        assert "1,234.56" in result.field_value

    def test_date_pattern(self):
        extractor = OcrExtractor()
        elements = [
            OcrTextElement("2024年1月15日", 100, 50, 250, 80),
        ]
        result = extractor._regex_match("开票日期", elements)
        assert result is not None
        assert "2024" in result.field_value

    def test_unknown_field_no_pattern(self):
        extractor = OcrExtractor()
        elements = [
            OcrTextElement("随便什么内容", 100, 50, 250, 80),
        ]
        result = extractor._regex_match("未知字段", elements)
        assert result is None


class TestTableMatch:
    """测试策略4: 表格结构匹配。"""

    def test_simple_table(self):
        extractor = OcrExtractor()
        elements = [
            OcrTextElement("名称", 50, 50, 150, 80),
            OcrTextElement("数量", 200, 50, 300, 80),
            OcrTextElement("单价", 350, 50, 450, 80),
            OcrTextElement("商品A", 50, 100, 150, 130),
            OcrTextElement("2", 200, 100, 250, 130),
            OcrTextElement("10.00", 350, 100, 420, 130),
        ]
        result = extractor._table_match("数量", elements)
        assert result is not None
        assert result.field_value == "2"

    def test_table_with_fuzzy_header(self):
        extractor = OcrExtractor()
        elements = [
            OcrTextElement("品名", 50, 50, 120, 80),
            OcrTextElement("金额", 200, 50, 300, 80),
            OcrTextElement("苹果", 50, 100, 120, 130),
            OcrTextElement("5.00", 200, 100, 260, 130),
        ]
        result = extractor._table_match("合计金额", elements)
        # 金额列可能匹配到 "金额"
        if result:
            assert result.field_value == "5.00"

    def test_table_header_not_found(self):
        extractor = OcrExtractor()
        elements = [
            OcrTextElement("A", 50, 50, 100, 80),
            OcrTextElement("B", 150, 50, 200, 80),
        ]
        result = extractor._table_match("发票代码", elements)
        assert result is None

    def test_table_too_few_elements(self):
        extractor = OcrExtractor()
        elements = [
            OcrTextElement("名称", 50, 50, 150, 80),
        ]
        result = extractor._table_match("名称", elements)
        assert result is None


class TestCoordinateCorrectness:
    """测试坐标计算正确性。"""

    def test_bbox_origin_top_left(self):
        """验证坐标系统以左上角为原点。"""
        elem = OcrTextElement("A", 0, 0, 50, 20)
        assert elem.x_min == 0
        assert elem.y_min == 0
        assert elem.bbox[0] == 0
        assert elem.bbox[1] == 0

    def test_bbox_conversion(self):
        """验证从 (x, y, w, h) 到 [x_min, y_min, x_max, y_max] 的转换。"""
        x, y, w, h = 100, 200, 300, 50
        elem = OcrTextElement("test", x_min=x, y_min=y, x_max=x + w, y_max=y + h)
        assert elem.bbox == [x, y, x + w, y + h]
        assert elem.x_max - elem.x_min == w
        assert elem.y_max - elem.y_min == h

    def test_multiple_elements_coordinate_independence(self):
        """验证多个元素的坐标互不干扰。"""
        elements = [
            OcrTextElement("A", 10, 20, 60, 40),
            OcrTextElement("B", 100, 200, 180, 240),
        ]
        assert elements[0].bbox == [10, 20, 60, 40]
        assert elements[1].bbox == [100, 200, 180, 240]
        assert elements[0].x_min != elements[1].x_min

    def test_center_calculation(self):
        """验证中心点计算。"""
        elem = OcrTextElement("test", 0, 0, 100, 100)
        assert elem.center_x == 50.0
        assert elem.center_y == 50.0


class TestExtractionPipeline:
    """测试完整的提取流水线。"""

    def test_priority_order_exact_first(self):
        """验证策略优先级: exact_match 优先于其他策略。"""
        extractor = OcrExtractor()
        elements = [
            OcrTextElement("发票代码: 1234567890", 50, 50, 300, 80),
        ]
        result = extractor._extract_field("发票代码", elements)
        assert result is not None
        assert result.extraction_method == "exact_match"

    def test_fallback_to_fuzzy(self):
        """验证精确匹配失败后回退到模糊匹配。"""
        extractor = OcrExtractor()
        elements = [
            OcrTextElement("发票代码", 50, 50, 150, 80),
            OcrTextElement("1234567890", 200, 50, 350, 80),
        ]
        result = extractor._extract_field("发票代码", elements)
        assert result is not None
        assert result.extraction_method == "kv_pair"

    def test_all_fields_empty(self):
        """验证所有字段提取失败时返回空结果。"""
        extractor = OcrExtractor()
        elements = [
            OcrTextElement("一些不相关的文本", 50, 50, 300, 80),
            OcrTextElement("更多随机内容", 50, 100, 300, 130),
        ]
        result = extractor._extract_field("发票代码", elements)
        assert result is None

    def test_empty_elements_list(self):
        """验证空元素列表时正常处理。"""
        extractor = OcrExtractor()
        result = extractor._extract_field("发票代码", [])
        assert result is None

    def test_extraction_with_confidence(self):
        """验证提取结果的置信度在合理范围内。"""
        extractor = OcrExtractor()
        elements = [
            OcrTextElement("发票代码: 1234567890", 50, 50, 300, 80),
        ]
        result = extractor._extract_field("发票代码", elements)
        assert result is not None
        assert 0.0 < result.confidence <= 1.0


class TestExtractFromLayout:
    """测试从 layout 结果中提取字段。"""

    def test_basic_layout_extraction(self):
        layout_result = {
            "image_size": (800, 600),
            "template_type": "full_a4",
            "rows": [
                {
                    "y_center": 50,
                    "elements": [
                        {"x": 50, "y": 30, "w": 150, "h": 30, "text": "发票代码:"},
                        {"x": 250, "y": 30, "w": 200, "h": 30, "text": "1234567890"},
                    ],
                },
                {
                    "y_center": 80,
                    "elements": [
                        {"x": 50, "y": 60, "w": 150, "h": 30, "text": "合计金额:"},
                        {"x": 250, "y": 60, "w": 100, "h": 30, "text": "999.00"},
                    ],
                },
            ],
        }
        result = extract_from_layout(layout_result, ["发票代码"])
        assert result["ocr_available"] is True
        assert result["image_size"] == (800, 600)

    def test_empty_layout(self):
        result = extract_from_layout({}, ["发票代码"])
        assert result["ocr_available"] is False
        assert len(result["errors"]) > 0


class TestOcrExtractorFileNotFound:
    """测试文件不存在的情况。"""

    def test_missing_file(self):
        extractor = OcrExtractor()
        result = extractor.extract("/nonexistent/file.png", ["发票代码"])
        assert result["ocr_available"] is False
        assert len(result["errors"]) > 0
        assert "文件不存在" in result["errors"][0]


class TestConvenienceFunctions:
    """测试便捷函数。"""

    def test_extract_ocr_fields_missing_file(self):
        result = extract_ocr_fields("/nonexistent/file.png", ["发票代码"])
        assert len(result["errors"]) > 0

    def test_extract_from_layout_with_partial_rows(self):
        layout_result = {
            "image_size": (1200, 800),
            "template_type": "partial_rows",
            "rows": [
                {
                    "y_center": 100,
                    "elements": [
                        {"x": 100, "y": 80, "w": 120, "h": 40, "text": "发票代码"},
                        {"x": 300, "y": 80, "w": 180, "h": 40, "text": "NO123456"},
                    ],
                },
            ],
        }
        result = extract_from_layout(layout_result, ["发票代码"])
        assert result["ocr_available"] is True
        assert len(result["fields"]) == 1
        assert result["fields"][0]["field_name"] == "发票代码"
        assert result["fields"][0]["field_value"] == "NO123456"