sourceafEfan::EfanMetaData.fan

using afPlastic::SrcCodeSnippet

** Provides meta data for an efan template.
** 
** @see `EfanRenderer.efanMetaData`
const class EfanMetaData {

    ** The 'ctx' type the renderer was compiled against.
    const Type? ctxType

    ** The name of the 'ctx' variable the renderer was compiled with.
    const Str ctxName

    ** Where the efan template originated from. Example, 'file://layout.efan'. 
    const Uri srcLocation

    ** The efan template source code.
    const Str efanTemplate

    ** The generated efan fantom code (for the inquisitive).
    const Str efanSrcCode

    ** A unique ID for the efan template. Defaults to the fully qualified type name.
    const Str templateId
    
    internal const Int srcCodePadding

    @NoDoc
    new make(|This|? in := null) { in?.call(this) }

    internal Void throwCompilationErr(Err cause, Int srcCodeLineNo) {
        templateLineNo  := findTemplateLineNo(srcCodeLineNo) ?: throw cause
        srcCode         := SrcCodeSnippet(srcLocation, efanTemplate)
        throw EfanCompilationErr(srcCode, templateLineNo, cause.msg, srcCodePadding, cause)
    }
    
    internal Void throwRuntimeErr(Err cause, Int srcCodeLineNo) {
        templateLineNo  := findTemplateLineNo(srcCodeLineNo) ?: throw cause
        srcCode         := SrcCodeSnippet(srcLocation, efanTemplate)
        throw EfanRuntimeErr(srcCode, templateLineNo, cause.msg, srcCodePadding, cause)
    }
    
    private Int? findTemplateLineNo(Int srcCodeLineNo) {
        fanLineNo       := srcCodeLineNo - 1    // from 1 to 0 based
        reggy           := Regex<|\s+?// \(efan\) --> ([0-9]+)$|>
        efanLineNo      := (Int?) null
        fanCodeLines    := efanSrcCode.splitLines
        
        while (fanLineNo > 0 && efanLineNo == null) {
            code := fanCodeLines[fanLineNo]
            reg := reggy.matcher(code)
            if (reg.find) {
                efanLineNo = reg.group(1).toInt
            } else {
                fanLineNo--
            }
        }
        
        return efanLineNo
    }
}