sourceafEfan::EfanTemplates.fan

using afIoc::Inject
using afIoc::ConcurrentCache

** Renders Embedded Fantom (efan) templates against a given context.
const mixin EfanTemplates {

    ** Renders the given template with the ctx.
    ** 
    ** WARN: Overuse of this method could cause a memory leak! A new Fantom Type is created on 
    ** every call. 
    abstract Str renderFromStr(Str efan, Obj? ctx := null)
    
    ** Renders an '.efan' template file with the given ctx. 
    ** The compiled '.efan' template is cached for re-use.   
    abstract Str renderFromFile(File efanFile, Obj? ctx := null)
    
}

internal const class EfanTemplatesImpl : EfanTemplates {
    private const static Log log := Utils.getLog(EfanTemplates#)
    private const FileCache fileCache
    
    @Inject private const EfanCompiler      compiler
    @Inject private const EfanViewHelpers   viewHelpers

    internal new make(|This|in) {
        in(this) 
        fileCache = FileCache(10sec)    // TODO: make config
    }

    override Str renderFromStr(Str efan, Obj? ctx := null) {
        renderer    := compiler.compile(`rendered/from/str`, efan, ctx?.typeof, viewHelpers.mixins)
        return renderer->render(ctx)
    }

    override Str renderFromFile(File efanFile, Obj? ctx := null) {
        if (!efanFile.exists)
            throw IOErr(ErrMsgs.templatesFileNotFound(efanFile))

        renderer := fileCache.getOrAddOrUpdate(efanFile) |->Obj| {
            template    := efanFile.readAllStr
            renderer    := compiler.compile(efanFile.normalize.uri, template, ctx?.typeof, viewHelpers.mixins)
            return renderer         
        }

        if (ctx != null) {
            ctxType := renderer->ctxType
            if (ctxType == null || !ctx.typeof.fits(ctxType)) {
                log.warn(LogMsgs.templatesCtxDoesNotFitRendererCts(ctx.typeof, renderer->ctxType, efanFile))
                template    := efanFile.readAllStr
                renderer    = compiler.compile(efanFile.normalize.uri, template, ctx?.typeof, viewHelpers.mixins)
                fileCache[efanFile] = renderer
            }
        }
        
        return renderer->render(ctx)
    }
}