package astruct

import (
	"encoding/json"
	"fmt"
	"log"
	"os"
	"reflect"
	"strings"

	"golang.org/x/exp/maps"
	"golang.org/x/exp/slices"
)

type Map map[string]reflect.Kind

// The main structure to use with astruct
//
// This structure contains options to configure behavior and methods in which to parse (JSON) and output (structs in source code)
type Astruct struct {
	// Options

	Use32Bit            bool   // Defaults to false, using 64-bit int and 64-bit float, when true, uses 32-bit variants of int and float
	UseAny              bool   // Defaults to true, when true the key word any (which is an alias to interface{}) will be used, when false an error will be thrown (this only applies to arrays/slices who have varying types)
	VerboseLogging      bool   // Dump verbose info into logs (User must setup log first!)
	AssumeStruct        bool   // Defaults to true, when true instead of a map of a basic type a structure will be made (even if the type matches), while false a map could be used in places where the type matches
	PrefixStructName    string // If not an empty "" string, Structures will be prefixed (for cases where you're going to have a single file produced with various structures from astruct, helps prevent name collisions, which would normally error out)
	SuffixForArrayLikes string // If not empty "" string, and it's an array this suffix is added (default's to "Item")

	// In-Memory Data (This data is gathered to form final products)
	// Almost all of these will be key being field name for in a structure (if one needs to be built) and value of reflect.Kind to determine:
	// 1. If the given thing was seen before (as with the case of say an []struct) or if that isn't possible as it's something else (in which a structure might not be possible)
	// 2. If a map is actually better represented as a structure (In the case of AssumeStruct the map won't be an option instead a map[string]struct would be used, or even []struct)

	MapLikes   map[string]Map            // Holds map-like structures which might be better defined as structures if they have varying types (else it will retain a single type being a map)
	ArrayLikes map[string][]reflect.Kind // Holds array-like structures (this includes slices) which might be able to be defined as arrays (but if varying types are encountered then it might end up as []any or []interface{})
	Parent     any                       // Position just above the Current position (for when we're done parsing this "depth", or if this is nil to indicate we're done)
	Depth      uint                      // Tracks how many nested structures (map, array/slice) deep we are
}

// Initializes to default options (this also resets the In-Memory Data to an initialized state)
func (A *Astruct) Defaults() {
	A.Use32Bit = false
	A.UseAny = true
	A.VerboseLogging = false
	A.AssumeStruct = true
	A.PrefixStructName = ""
	A.SuffixForArrayLikes = "Item"
	A.Init()
}

// This resets the In-Memory Data to an initialized state
func (A *Astruct) Init() {
	A.MapLikes = make(map[string]Map)
	A.ArrayLikes = make(map[string][]reflect.Kind)
	A.Parent = nil
	A.Depth = 0
}

// Creates a new Astruct, if given a Prefix for generated structs (only the first one) will be used
func NewAstruct(PrefixStructName ...string) *Astruct {
	A := &Astruct{}
	A.Defaults()
	if len(PrefixStructName) != 0 {
		A.PrefixStructName = CamelCase(PrefixStructName[0])
	}
	return A
}

func (A *Astruct) ReadFile(filename string) error {
	data, err := os.ReadFile(filename)
	if err != nil {
		return fmt.Errorf("astruct.Astruct.ReadFile(filename='%s') On os.ReadFile > %w", filename, err)
	}
	var root map[string]any
	err = json.Unmarshal(data, &root)
	if err != nil {
		return fmt.Errorf("astruct.Astruct.ReadFile(filename='%s') On json.Unmarshal > %w", filename, err)
	}
	// Begin parsing...
	A.parse(root, "")
	return nil
}

func (A *Astruct) parse(at any, name string) error {
	switch reflect.TypeOf(at).Kind() {
	case reflect.Map:
		m := at.(map[string]any)
		var last_type reflect.Kind = 0
		var same_type bool = true
		for k, v := range m {
			if A.VerboseLogging {
				log.Printf(strings.Repeat("  ", int(A.Depth))+"'%s' = %s", k, reflect.TypeOf(v).Kind().String())
			}
			if same_type {
				if last_type == 0 {
					last_type = reflect.TypeOf(v).Kind()
				} else if reflect.TypeOf(v).Kind() != last_type {
					same_type = false
				}
			}
			switch reflect.TypeOf(v).Kind() {
			case reflect.Map:
				A.Depth += 1
				err := A.parse(v, k)
				if err != nil {
					return err
				}
				A.Depth -= 1
			case reflect.Array, reflect.Slice:
				A.Depth += 1
				err := A.parse(v, k)
				if err != nil {
					return err
				}
				A.Depth -= 1
			}
		}
		A.MapLikes[name] = make(Map)
		if !same_type {
			for k, v := range m {
				if reflect.TypeOf(v).Kind() == reflect.Float32 || reflect.TypeOf(v).Kind() == reflect.Float64 {
					f := v.(float64)
					if IsInt(f) {
						A.MapLikes[name][k] = reflect.Int64
					} else {
						A.MapLikes[name][k] = reflect.Float64
					}
				} else {
					A.MapLikes[name][k] = reflect.TypeOf(v).Kind()
				}
			}
		} else { // We'll use a empty string "", to indicate this map is same type
			A.MapLikes[name][""] = reflect.TypeOf(m[maps.Keys(m)[0]]).Kind()
			for k, v := range m {
				if reflect.TypeOf(v).Kind() == reflect.Float32 || reflect.TypeOf(v).Kind() == reflect.Float64 {
					f := v.(float64)
					if IsInt(f) {
						A.MapLikes[name][k] = reflect.Int64
					} else {
						A.MapLikes[name][k] = reflect.Float64
					}
				} else {
					A.MapLikes[name][k] = reflect.TypeOf(v).Kind()
				}
			}
		}
	case reflect.Array, reflect.Slice:
		a := at.([]any)
		var last_type reflect.Kind = 0
		var same_type bool = true
		for i, v := range a {
			if A.VerboseLogging {
				log.Printf(strings.Repeat("  ", int(A.Depth))+"%d = %s", i, reflect.TypeOf(v).Kind().String())
			}
			if same_type {
				if last_type == 0 {
					last_type = reflect.TypeOf(v).Kind()
				} else if reflect.TypeOf(v).Kind() != last_type {
					same_type = false
				}
			}
			switch reflect.TypeOf(v).Kind() {
			case reflect.Map:
				A.Depth += 1
				err := A.parse(v, A.SuffixForArrayLikes)
				if err != nil {
					return err
				}
				A.Depth -= 1
			case reflect.Array, reflect.Slice:
				A.Depth += 1
				err := A.parse(v, A.SuffixForArrayLikes)
				if err != nil {
					return err
				}
				A.Depth -= 1
			}
		}
		A.ArrayLikes[name] = []reflect.Kind{}
		if !same_type {
			for _, v := range a {
				if reflect.TypeOf(v).Kind() == reflect.Float32 || reflect.TypeOf(v).Kind() == reflect.Float64 {
					f := v.(float64)
					if IsInt(f) {
						A.ArrayLikes[name] = append(A.ArrayLikes[name], reflect.Int64)
					} else {
						A.ArrayLikes[name] = append(A.ArrayLikes[name], reflect.Float64)
					}
				} else {
					A.ArrayLikes[name] = append(A.ArrayLikes[name], reflect.TypeOf(v).Kind())
				}
			}
		} else {
			v := a[0]
			if reflect.TypeOf(v).Kind() == reflect.Float32 || reflect.TypeOf(v).Kind() == reflect.Float64 {
				f := v.(float64)
				if IsInt(f) {
					A.ArrayLikes[name] = append(A.ArrayLikes[name], reflect.Int64)
				} else {
					A.ArrayLikes[name] = append(A.ArrayLikes[name], reflect.Float64)
				}
			} else {
				A.ArrayLikes[name] = append(A.ArrayLikes[name], reflect.TypeOf(v).Kind())
			}
		}
	default:
		if A.VerboseLogging {
			log.Printf(strings.Repeat("  ", int(A.Depth))+"%s", reflect.TypeOf(at).Kind().String())
		}
	}
	return nil
}

// Checks if the given JSON Number (represented as float64) can be a int64 instead
func IsInt(v float64) bool {
	str := fmt.Sprintf("%f", v)
	var hit_dot bool = false
	for _, r := range str {
		if r == '.' {
			hit_dot = true
			continue
		}
		if hit_dot {
			if r != '0' {
				return false
			}
		}
	}
	return true
}

// Checks if the given data (either map or array/slice) contains the same types
//
// Used to identify if a map or array/slice could be used (unless AssumeStruct is true in which a struct will always be made)
func SameType(data any) bool {
	if reflect.TypeOf(data) == reflect.TypeOf(Map{}) {
		m := data.(Map)
		var last_type reflect.Kind = 0
		for _, v := range m {
			if last_type == 0 {
				last_type = v
			} else if v != last_type {
				return false
			}
		}
		return true
	}
	switch reflect.TypeOf(data).Kind() {
	case reflect.Map:
		m := data.(map[string]any)
		var last_type reflect.Kind = 0
		for _, v := range m {
			if last_type == 0 {
				last_type = reflect.TypeOf(v).Kind()
			} else if reflect.TypeOf(v).Kind() != last_type {
				return false
			}
		}
		return true
	case reflect.Array, reflect.Slice:
		a := data.([]any)
		var last_type reflect.Kind = 0
		for _, v := range a {
			if last_type == 0 {
				last_type = reflect.TypeOf(v).Kind()
			} else if reflect.TypeOf(v).Kind() != last_type {
				return false
			}
		}
		return true
	}
	return false
}

func CamelCase(field string) string {
	if len(field) == 0 {
		return ""
	}
	var result string
	if !strings.Contains(field, " ") || !strings.Contains(field, "-") {
		result += strings.ToUpper(string(field[0]))
		result += field[1:]
		return result
	}
	result = strings.ToTitle(field)
	result = strings.ReplaceAll(result, " ", "")
	result = strings.ReplaceAll(result, "-", "")
	return result
}

func (A *Astruct) WriteFile(filename, packageName string, permissions os.FileMode) error {
	if packageName == "" {
		return fmt.Errorf("astruct.Astruct.WriteFile(filename='%s', packageName='%s', permissions=%d) > %s", filename, packageName, permissions, "Missing 'packageName', this must not be empty!")
	}
	var successful bool = true
	fh, err := os.OpenFile(filename, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, permissions)
	if err != nil {
		return fmt.Errorf("astruct.Astruct.WriteFile(filename='%s', packageName='%s', permissions=%d) On os.OpenFile > %w", filename, packageName, permissions, err)
	}
	defer func() {
		fh.Close()
		if !successful {
			err = os.Remove(filename)
			if err != nil {
				log.Panicf("astruct.Astruct.WriteFile(filename='%s', packageName='%s', permissions=%d) On os.Remove > %v", filename, packageName, permissions, err)
			}
		}
	}()
	fh.WriteString(fmt.Sprintf("package %s\n\n", packageName))
	//var slices_to_structs []string = []string{}
	var seen []string = []string{}
	for name, m := range A.MapLikes {
		/*if name == "" { // Ignore the root node for now
			continue
		}*/
		if slices.Contains(seen, name) {
			continue
		}
		_, sameType := m[""] // Check if the empty string exists in this map (if it does it contains same typed data)
		if !A.AssumeStruct || !sameType {
			fh.WriteString(fmt.Sprintf("type %s%s struct {\n", A.PrefixStructName, CamelCase(name)))
			for k, v := range m {
				if slices.Contains(maps.Keys(A.MapLikes), k) {
					_, sameType2 := A.MapLikes[k][""]
					if sameType2 && !A.AssumeStruct {
						fh.WriteString(fmt.Sprintf("\t%s map[string]%s\n", CamelCase(k), A.MapLikes[k][""].String()))
						seen = append(seen, k)
					} else if !sameType2 || A.AssumeStruct && v == reflect.Map {
						fh.WriteString(fmt.Sprintf("\t%s %s%s\n", CamelCase(k), A.PrefixStructName, CamelCase(k)))
					} else if !sameType2 || A.AssumeStruct && v != reflect.Map {
						fh.WriteString(fmt.Sprintf("\t%s %s\n", CamelCase(k), v.String()))
					}
				} else {
					if slices.Contains(maps.Keys(A.ArrayLikes), k) {
						a := A.ArrayLikes[k]
						if len(a) == 1 {
							if a[0] == reflect.Float64 && A.Use32Bit {
								fh.WriteString(fmt.Sprintf("\t%s []float32\n", CamelCase(k)))
								continue
							} else if a[0] == reflect.Int64 && A.Use32Bit {
								fh.WriteString(fmt.Sprintf("\t%s []int32\n", CamelCase(k)))
								continue
							} else if a[0] == reflect.Map {
								fh.WriteString(fmt.Sprintf("\t%s []%s%s\n", CamelCase(k), CamelCase(k), A.SuffixForArrayLikes))
								continue
							}
							fh.WriteString(fmt.Sprintf("\t%s []%s\n", CamelCase(k), a[0]))
						} else {
							//fh.WriteString(fmt.Sprintf("\t%s []%s\n", CamelCase(k), CamelCase(k)))
							//slices_to_structs = append(slices_to_structs, k)
							if A.UseAny {
								fh.WriteString(fmt.Sprintf("\t%s []any\n", CamelCase(k)))
							} else {
								return fmt.Errorf("astruct.Astruct.WriteFile(filename='%s', packageName='%s', permissions=%d) > Field '%s' is a slice, but it contains varying types (!UseAny, !UseInterface)", filename, packageName, permissions, k)
							}
						}
					} else {
						if v == reflect.Float64 && A.Use32Bit {
							fh.WriteString(fmt.Sprintf("\t%s float32\n", CamelCase(k)))
							continue
						} else if v == reflect.Int64 && A.Use32Bit {
							fh.WriteString(fmt.Sprintf("\t%s int32\n", CamelCase(k)))
							continue
						}
						fh.WriteString(fmt.Sprintf("\t%s %s\n", CamelCase(k), v.String()))
					}
				}
			}
			fh.WriteString("}\n\n")
		} else if A.AssumeStruct && sameType {
			fh.WriteString(fmt.Sprintf("type %s%s struct {\n", A.PrefixStructName, CamelCase(name)))
			t := m[""]
			var kind reflect.Kind
			if t == reflect.Float64 && A.Use32Bit {
				kind = reflect.Float32
			} else if t == reflect.Int64 && A.Use32Bit {
				kind = reflect.Int32
			} else {
				kind = t
			}
			for k := range m {
				if k == "" {
					continue
				}
				fh.WriteString(fmt.Sprintf("\t%s %s\n", CamelCase(k), kind))
			}
			fh.WriteString("}\n\n")
		}
	}
	/*
		for _, name := range slices_to_structs {
			fh.WriteString(fmt.Sprintf("type %s%s struct {\n", A.PrefixStructName, name))
			for _,
		}
	*/
	return nil
}