package codegen

import (
    "github.com/zelenin/go-tdlib/tlparser"
    "fmt"
    "bytes"
)

func GenerateUnmarshalers(schema *tlparser.Schema, packageName string) []byte {
    buf := bytes.NewBufferString("")

    buf.WriteString(fmt.Sprintf("%s\n\npackage %s\n\n", header, packageName))

    buf.WriteString(`import (
    "encoding/json"
    "fmt"
)

`)

    for _, class := range schema.Classes {
        tdlibClass := TdlibClass(class.Name, schema)

        buf.WriteString(fmt.Sprintf(`func Unmarshal%s(data json.RawMessage) (%s, error) {
    var meta meta

    err := json.Unmarshal(data, &meta)
    if err != nil {
        return nil, err
    }

    switch meta.Type {
`, tdlibClass.ToGoType(), tdlibClass.ToGoType()))

        for _, subType := range tdlibClass.GetSubTypes() {
            buf.WriteString(fmt.Sprintf(`    case %s:
        return Unmarshal%s(data)

`, subType.ToTypeConst(), subType.ToGoType()))

        }

        buf.WriteString(`    default:
        return nil, fmt.Errorf("Error unmarshaling. Unknown type: " +  meta.Type)
    }
}

`)
    }

    for _, typ := range schema.Types {
        tdlibType := TdlibType(typ.Name, schema)

        if tdlibType.IsList() || tdlibType.IsInternal() {
            continue
        }

        buf.WriteString(fmt.Sprintf(`func Unmarshal%s(data json.RawMessage) (*%s, error) {
    var resp %s

    err := json.Unmarshal(data, &resp)

    return &resp, err
}

`, tdlibType.ToGoType(), tdlibType.ToGoType(), tdlibType.ToGoType()))

    }

    buf.WriteString(`func UnmarshalType(data json.RawMessage) (Type, error) {
    var meta meta

    err := json.Unmarshal(data, &meta)
    if err != nil {
        return nil, err
    }

    switch meta.Type {
`)

    for _, typ := range schema.Types {
        tdlibType := TdlibType(typ.Name, schema)

        if tdlibType.IsList() || tdlibType.IsInternal() {
            continue
        }

        buf.WriteString(fmt.Sprintf(`    case %s:
        return Unmarshal%s(data)

`, tdlibType.ToTypeConst(), tdlibType.ToGoType()))

    }

    buf.WriteString(`    default:
        return nil, fmt.Errorf("Error unmarshaling. Unknown type: " +  meta.Type)
    }
}
`)

    return buf.Bytes()
}