// Copyright 2017 gf Author(https://gitee.com/johng/gf). All Rights Reserved.
//
// This Source Code Form is subject to the terms of the MIT License.
// If a copy of the MIT was not distributed with this file,
// You can obtain one at https://gitee.com/johng/gf.

// 视图管理
package gview

import (
    "sync"
    "bytes"
    "errors"
    "strings"
    "html/template"
    "gitee.com/johng/gf/g/os/gfile"
    "gitee.com/johng/gf/g/container/gmap"
)

// 视图对象
type View struct {
    mu       sync.RWMutex
    path     string                  // 模板目录(绝对路径)
    funcmap  map[string]interface{}  // FuncMap
    contents *gmap.StringStringMap   // 已解析的模板文件内容
}

// 视图表
var viewMap = gmap.NewStringInterfaceMap()

// 获取或者创建一个视图对象
func Get(path string) *View {
    if r := viewMap.Get(path); r != nil {
        return r.(*View)
    }
    v := New(path)
    viewMap.Set(path, v)
    return v
}

// 生成一个视图对象
func New(path string) *View {
    view := &View {
        path     : path,
        funcmap  : make(map[string]interface{}),
        contents : gmap.NewStringStringMap(),
    }
    view.BindFunc("include", view.funcInclude)
    return view
}

// 设置模板目录绝对路径
func (view *View) SetPath(path string) {
    view.mu.Lock()
    defer view.mu.Unlock()
    view.path = path
}

// 获取模板目录绝对路径
func (view *View) GetPath() string {
    view.mu.RLock()
    defer view.mu.RUnlock()
    return view.path
}

// 获取模板文件内容
func (view *View) GetTplContent() string {
    view.mu.RLock()
    defer view.mu.RUnlock()
    return view.path
}

// 直接解析模板，返回解析后的内容
func (view *View) Parse(file string, params map[string]interface{}) ([]byte, error) {
    // 获取模板文件路径及内容
    path    := strings.TrimRight(view.GetPath(), gfile.Separator) + gfile.Separator + file
    content := view.contents.Get(path)
    if content == "" {
        content = gfile.GetContents(path)
        if content == "" {
            content = gfile.GetContents(file)
        }
        view.contents.Set(path, content)
    }
    if content == "" {
        return nil, errors.New("invalid tpl \"" + file + "\"")
    }
    // 执行模板解析
    buffer := bytes.NewBuffer(nil)
    if tpl, err := template.New(path).Funcs(view.getFuncs()).Parse(content); err != nil {
        return nil, err
    } else {
        if err := tpl.Execute(buffer, params); err != nil {
            return nil, err
        }
    }
    return buffer.Bytes(), nil
}

// 绑定自定义函数，该函数是全局有效，即调用之后每个线程都会生效，因此有并发安全控制
func (view *View) BindFunc(name string, function interface{}) {
    view.mu.Lock()
    defer view.mu.Unlock()
    view.funcmap[name] = function
}

// 获取模板自定义函数，每一次都是一份拷贝
func (view *View) getFuncs() map[string]interface{} {
    m := make(map[string]interface{})
    view.mu.RLock()
    for k, v := range view.funcmap {
        m[k] = v
    }
    view.mu.RUnlock()
    return m
}

// 模板内置方法：include
func (view *View) funcInclude(file string, datas...map[string]interface{}) template.HTML {
    var data map[string]interface{} = nil
    if len(datas) > 0 {
        data = datas[0]
    }
    content, err := view.Parse(file, data)
    if err != nil {
        return template.HTML(err.Error())
    }
    return template.HTML(content)
}