package codegen

import (
	"github.com/dave/jennifer/jen"
	"sort"
	"unicode"
)

// join appends a bunch of Go Code together, each on their own line.
func join(s []jen.Code) *jen.Statement {
	r := jen.Empty()
	for i, stmt := range s {
		if i > 0 {
			r.Line()
		}
		r.Add(stmt)
	}
	return r
}

// Struct defines a struct-based type, its functions, and its methods for Go
// code generation.
type Struct struct {
	comment      string
	name         string
	methods      map[string]*Method
	constructors map[string]*Function
	members      []jen.Code
}

// NewStruct creates a new commented Struct type.
func NewStruct(comment string,
	name string,
	methods []*Method,
	constructors []*Function,
	members []jen.Code) *Struct {
	s := &Struct{
		comment:      comment,
		name:         name,
		methods:      make(map[string]*Method, len(methods)),
		constructors: make(map[string]*Function, len(constructors)),
		members:      members,
	}
	for _, m := range methods {
		s.methods[m.Name()] = m
	}
	for _, c := range constructors {
		s.constructors[c.Name()] = c
	}
	return s
}

// Definition generates the Go code required to define and implement this
// struct, its methods, and its functions.
func (s *Struct) Definition() jen.Code {
	comment := jen.Empty()
	if len(s.comment) > 0 {
		comment = jen.Commentf(insertNewlines(s.comment)).Line()
	}
	def := comment.Type().Id(s.name).Struct(
		join(s.members),
	)
	// Sort the functions and methods.
	fs := make([]string, 0, len(s.constructors))
	for _, c := range s.constructors {
		fs = append(fs, c.Name())
	}
	ms := make([]string, 0, len(s.methods))
	for _, m := range s.methods {
		ms = append(ms, m.Name())
	}
	sort.Sort(sort.StringSlice(fs))
	sort.Sort(sort.StringSlice(ms))
	// Add the functions and methods in order.
	for _, c := range fs {
		def = def.Line().Line().Add(s.constructors[c].Definition())
	}
	for _, m := range ms {
		def = def.Line().Line().Add(s.methods[m].Definition())
	}
	return def
}

// Method obtains the Go code to be generated for the method with a specific
// name. Panics if no such method exists.
func (s *Struct) Method(name string) *Method {
	return s.methods[name]
}

// Constructors obtains the Go code to be generated for the function with a
// specific name. Panics if no such function exists.
func (s *Struct) Constructors(name string) *Function {
	return s.constructors[name]
}

// ToInterface creates an interface version of this struct.
func (s *Struct) ToInterface(pkg, name, comment string) *Interface {
	fns := make([]FunctionSignature, 0, len(s.methods))
	for _, m := range s.methods {
		if unicode.IsUpper([]rune(m.Name())[0]) {
			fns = append(fns, m.ToFunctionSignature())
		}
	}
	return NewInterface(pkg, name, fns, comment)
}