## Prerequisites

- Node.js 20.0 or higher

## Installation

```sh
git clone https://github.com/osisdie/node-seo-for-fun.git
cd node-seo-for-fun
npm install
```

### Run Locally (Web UI)

```sh
npm start # http://localhost:3000
# or with hot-reload:
npm run dev
```

Open `http://localhost:3000` to use the web-based SEO validator.

### Deploy to Vercel

```sh
npx vercel
```

Or click the **Deploy with Vercel** button above for one-click deployment.

## Config Your Rules

SEO rules are defined in the config file (**default**: `conf/config.json`)

### Default SEO syntax patterns
```json
"seo": {
"pattern": {
"existsTag": {
"xpath": "{{root}} {{tag}}",
"msg": "This HTML without <{{tag}}> tag"
},
"existsAttr": {
"xpath": "{{root}} {{tag}}[{{attr}}]",
"msg": "This HTML without <{{tag}} {{attr}}> tag"
},
"existsNoAttr": {
"xpath": "{{root}} {{tag}}:not([{{attr}}])",
"msg": "This HTML without <{{tag}} {{attr}}> tag"
},
"existsAttrVal": {
"xpath": "{{root}} {{tag}}[{{attr}}*={{value}}]",
"msg": "This HTML without <{{tag}} {{attr}}=\"{{value}}\"> tag"
},
"tagCountLessThan": {
"xpath": "{{root}} {{tag}}",
"msg": "This HTML have more than {{max}} <{{tag}}> tag"
}
}
}
```

### Predefined SEO rules 1~5 and custom rule 101

```json
"seo": {
"rules": {
"rule1": {
"ruleFor": [
{
"pattern": "seo:pattern:existsNoAttr",
"fn": "checkShouldNotExist",
"root": "html",
"tag": "img",
"attr": "alt"
}
]
},
"rule2": {
"ruleFor": [
{
"pattern": "seo:pattern:existsNoAttr",
"fn": "checkShouldNotExist",
"root": "html",
"tag": "a",
"attr": "rel"
}
]
},
"rule3": {
"ruleFor": [
{
"pattern": "seo:pattern:existsTag",
"fn": "checkShouldExist",
"root": "head",
"tag": "title",
"min": 1,
"max": 1
},
{
"pattern": "seo:pattern:existsAttrVal",
"fn": "checkShouldExist",
"root": "head",
"tag": "meta",
"attr": "name",
"value": "description",
"min": 1,
"max": 1
},
{
"pattern": "seo:pattern:existsAttrVal",
"fn": "checkShouldExist",
"root": "head",
"tag": "meta",
"attr": "name",
"value": "keywords",
"min": 1,
"max": 1
}
]
},
"rule4": {
"ruleFor": [
{
"pattern": "seo:pattern:tagCountLessThan",
"fn": "checkMaxOccurrence",
"root": "html",
"tag": "strong",
"max": 15,
"min": 0
}
]
},
"rule5": {
"ruleFor": [
{
"pattern": "seo:pattern:tagCountLessThan",
"fn": "checkMaxOccurrence",
"root": "html",
"tag": "h1",
"max": 1,
"min": 0
}
]
},
"rule101": {
"ruleFor": [
{
"pattern": "seo:pattern:existsAttrVal",
"fn": "checkShouldExist",
"root": "head",
"tag": "meta",
"attr": "name",
"value": "robots",
"min": 1,
"max": 1
}
]
}
}
}
```

## Unit Test

Run all tests:
```sh
npm test
```

**Sample output** (57 tests):
```
AppUtil() requires(/lib/app_util.js)
config
✔ path conf/config.json should exist
Function getCfgVal()
version
✔ app:version should be 0.1.0

SEOValidator() requires(/lib/seo/seo_validator.js)
Function validate()
pass, input:file, output:file
✔ rule1 should have 0 warning(s)
✔ rule2 should have 0 warning(s)
...
NOT pass, input:stream, output:console
✔ https://google.com.tw returns 3 warning(s)

SingleRuleParser() requires(/lib/seo/seo_validator.js)
Function checkConfigSyntax()
✔ correctly syntax (×11)
Function analysis()
✔ should return isSuccess with/without warnings (×14)

57 passing (2s)
```

### Test individual modules

```sh
# AppUtil config tests
npm test ./test/AppUtil_test.js

# Reader/Writer I/O tests
npm test ./test/app_fs_test.js

# Single rule syntax validation
npm test ./test/SingleRuleParser_test.js

# Full SEO validator integration tests
npm test ./test/SEOValidator_test.js
```

## Usage Example

```js
const fs = require('fs')
const { SEOValidator } = require('./lib/seo/seo_validator')
const { AppUtil } = require('./lib/app_util')
const { RuleInputEnum, RuleOutputEnum } = require('./lib/models/app_enum')

let readStream = fs.createReadStream('test/input/https___google_com_tw')
let validator = new SEOValidator()
.includeRules([1, 2, 3, 4, 5])
.setReader(AppUtil.createReader({ kind: RuleInputEnum.stream, stream: readStream }))
.setWriter(AppUtil.createWriter({ kind: RuleOutputEnum.file, path: 'test/output/result.out' }))