package types

import (
    "log"
    "runtime"
)

var (
    // EngineInitOptions的默认值
    defaultNumSegmenterThreads       = runtime.NumCPU()
    defaultNumShards                 = 2
    defaultIndexerBufferLength       = runtime.NumCPU()
    defaultNumIndexerThreadsPerShard = runtime.NumCPU()
    defaultRankerBufferLength        = runtime.NumCPU()
    defaultNumRankerThreadsPerShard  = runtime.NumCPU()
    defaultDefaultRankOptions        = RankOptions{
        ScoringCriteria: RankByBM25{},
    }
    defaultIndexerInitOptions = IndexerInitOptions{
        IndexType:      FrequenciesIndex,
        BM25Parameters: &defaultBM25Parameters,
    }
    defaultBM25Parameters = BM25Parameters{
        K1: 2.0,
        B:  0.75,
    }
    defaultPersistentStorageShards = 8
)

type EngineInitOptions struct {
    // 是否使用分词器
    // 默认使用，否则在启动阶段跳过SegmenterDictionaries和StopTokenFile设置
    // 如果你不需要在引擎内分词，可以将这个选项设为true
    // 注意，如果你不用分词器，那么在调用IndexDocument时DocumentIndexData中的Content会被忽略
    NotUsingSegmenter bool

    // 半角逗号分隔的字典文件，具体用法见
    // sego.Segmenter.LoadDictionary函数的注释
    SegmenterDictionaries string

    // 停用词文件
    StopTokenFile string

    // 分词器线程数
    NumSegmenterThreads int

    // 索引器和排序器的shard数目
    // 被检索/排序的文档会被均匀分配到各个shard中
    NumShards int

    // 索引器的信道缓冲长度
    IndexerBufferLength int

    // 索引器每个shard分配的线程数
    NumIndexerThreadsPerShard int

    // 排序器的信道缓冲长度
    RankerBufferLength int

    // 排序器每个shard分配的线程数
    NumRankerThreadsPerShard int

    // 索引器初始化选项
    IndexerInitOptions *IndexerInitOptions

    // 默认的搜索选项
    DefaultRankOptions *RankOptions

    // 是否使用持久数据库，以及数据库文件保存的目录和裂分数目
    UsePersistentStorage    bool
    PersistentStorageFolder string
    PersistentStorageShards int
}

// 初始化EngineInitOptions，当用户未设定某个选项的值时用默认值取代
func (options *EngineInitOptions) Init() {
    if !options.NotUsingSegmenter {
        if options.SegmenterDictionaries == "" {
            log.Fatal("字典文件不能为空")
        }
    }

    if options.NumSegmenterThreads == 0 {
        options.NumSegmenterThreads = defaultNumSegmenterThreads
    }

    if options.NumShards == 0 {
        options.NumShards = defaultNumShards
    }

    if options.IndexerBufferLength == 0 {
        options.IndexerBufferLength = defaultIndexerBufferLength
    }

    if options.NumIndexerThreadsPerShard == 0 {
        options.NumIndexerThreadsPerShard = defaultNumIndexerThreadsPerShard
    }

    if options.RankerBufferLength == 0 {
        options.RankerBufferLength = defaultRankerBufferLength
    }

    if options.NumRankerThreadsPerShard == 0 {
        options.NumRankerThreadsPerShard = defaultNumRankerThreadsPerShard
    }

    if options.IndexerInitOptions == nil {
        options.IndexerInitOptions = &defaultIndexerInitOptions
    }

    if options.IndexerInitOptions.BM25Parameters == nil {
        options.IndexerInitOptions.BM25Parameters = &defaultBM25Parameters
    }

    if options.DefaultRankOptions == nil {
        options.DefaultRankOptions = &defaultDefaultRankOptions
    }

    if options.DefaultRankOptions.ScoringCriteria == nil {
        options.DefaultRankOptions.ScoringCriteria = defaultDefaultRankOptions.ScoringCriteria
    }

    if options.PersistentStorageShards == 0 {
        options.PersistentStorageShards = defaultPersistentStorageShards
    }
}