package gorm

import (
	"fmt"
	"reflect"
	"strconv"
	"strings"
)

type callback struct {
	creates    []*func(scope *Scope)
	updates    []*func(scope *Scope)
	deletes    []*func(scope *Scope)
	queries    []*func(scope *Scope)
	rowQueries []*func(scope *Scope)
	processors []*callbackProcessor
}

type callbackProcessor struct {
	name      string
	before    string
	after     string
	replace   bool
	remove    bool
	typ       string
	processor *func(scope *Scope)
	callback  *callback
}

func (c *callback) addProcessor(typ string) *callbackProcessor {
	cp := &callbackProcessor{typ: typ, callback: c}
	c.processors = append(c.processors, cp)
	return cp
}

func (c *callback) clone() *callback {
	return &callback{
		creates:    c.creates,
		updates:    c.updates,
		deletes:    c.deletes,
		queries:    c.queries,
		processors: c.processors,
	}
}

func (c *callback) Create() *callbackProcessor {
	return c.addProcessor("create")
}

func (c *callback) Update() *callbackProcessor {
	return c.addProcessor("update")
}

func (c *callback) Delete() *callbackProcessor {
	return c.addProcessor("delete")
}

func (c *callback) Query() *callbackProcessor {
	return c.addProcessor("query")
}

func (c *callback) RowQuery() *callbackProcessor {
	return c.addProcessor("row_query")
}

func (cp *callbackProcessor) Before(name string) *callbackProcessor {
	cp.before = name
	return cp
}

func (cp *callbackProcessor) After(name string) *callbackProcessor {
	cp.after = name
	return cp
}

func (cp *callbackProcessor) Register(name string, fc func(scope *Scope)) {
	cp.name = name
	cp.processor = &fc
	cp.callback.sort()
}

func (cp *callbackProcessor) Remove(name string) {
	fmt.Printf("[info] removing callback `%v` from %v\n", name, fileWithLineNum())
	cp.name = name
	cp.remove = true
	cp.callback.sort()
}

func (cp *callbackProcessor) Replace(name string, fc func(scope *Scope)) {
	fmt.Printf("[info] replacing callback `%v` from %v\n", name, fileWithLineNum())
	cp.name = name
	cp.processor = &fc
	cp.replace = true
	cp.callback.sort()
}

func getRIndex(strs []string, str string) int {
	for i := len(strs) - 1; i >= 0; i-- {
		if strs[i] == str {
			return i
		}
	}
	return -1
}

func sortProcessors(cps []*callbackProcessor) []*func(scope *Scope) {
	var sortCallbackProcessor func(c *callbackProcessor)
	var names, sortedNames = []string{}, []string{}

	for _, cp := range cps {
		if index := getRIndex(names, cp.name); index > -1 {
			if !cp.replace && !cp.remove {
				fmt.Printf("[warning] duplicated callback `%v` from %v\n", cp.name, fileWithLineNum())
			}
		}
		names = append(names, cp.name)
	}

	sortCallbackProcessor = func(c *callbackProcessor) {
		if getRIndex(sortedNames, c.name) > -1 {
			return
		}

		if len(c.before) > 0 {
			if index := getRIndex(sortedNames, c.before); index > -1 {
				sortedNames = append(sortedNames[:index], append([]string{c.name}, sortedNames[index:]...)...)
			} else if index := getRIndex(names, c.before); index > -1 {
				sortedNames = append(sortedNames, c.name)
				sortCallbackProcessor(cps[index])
			} else {
				sortedNames = append(sortedNames, c.name)
			}
		}

		if len(c.after) > 0 {
			if index := getRIndex(sortedNames, c.after); index > -1 {
				sortedNames = append(sortedNames[:index+1], append([]string{c.name}, sortedNames[index+1:]...)...)
			} else if index := getRIndex(names, c.after); index > -1 {
				cp := cps[index]
				if len(cp.before) == 0 {
					cp.before = c.name
				}
				sortCallbackProcessor(cp)
			} else {
				sortedNames = append(sortedNames, c.name)
			}
		}

		if getRIndex(sortedNames, c.name) == -1 {
			sortedNames = append(sortedNames, c.name)
		}
	}

	for _, cp := range cps {
		sortCallbackProcessor(cp)
	}

	var funcs = []*func(scope *Scope){}
	var sortedFuncs = []*func(scope *Scope){}
	for _, name := range sortedNames {
		index := getRIndex(names, name)
		if !cps[index].remove {
			sortedFuncs = append(sortedFuncs, cps[index].processor)
		}
	}

	for _, cp := range cps {
		if sindex := getRIndex(sortedNames, cp.name); sindex == -1 {
			if !cp.remove {
				funcs = append(funcs, cp.processor)
			}
		}
	}

	return append(sortedFuncs, funcs...)
}

func (c *callback) sort() {
	var creates, updates, deletes, queries, rowQueries []*callbackProcessor

	for _, processor := range c.processors {
		switch processor.typ {
		case "create":
			creates = append(creates, processor)
		case "update":
			updates = append(updates, processor)
		case "delete":
			deletes = append(deletes, processor)
		case "query":
			queries = append(queries, processor)
		case "row_query":
			rowQueries = append(rowQueries, processor)
		}
	}

	c.creates = sortProcessors(creates)
	c.updates = sortProcessors(updates)
	c.deletes = sortProcessors(deletes)
	c.queries = sortProcessors(queries)
	c.rowQueries = sortProcessors(rowQueries)
}

func ForceReload(scope *Scope) {
	if _, ok := scope.InstanceGet("gorm:force_reload"); ok {
		scope.DB().New().First(scope.Value)
	}
}

func escapeIfNeeded(scope *Scope, value string) string {
	trimmed := strings.TrimSpace(value)
	// default:'string value' OR
	if (strings.HasPrefix(trimmed, "'") && strings.HasSuffix(trimmed, "'")) ||
		strings.HasSuffix(trimmed, ")") { //sql expression, like: default:"(now() at timezone 'utc') or now() or user_defined_function(parameters.. )
		return trimmed
	}

	lowered := strings.ToLower(trimmed)
	if lowered == "null" || strings.HasPrefix(lowered, "current_") { // null and other sql reserved keyworks (used a default values) can't be placed between apices
		return lowered
	}
	return scope.AddToVars(trimmed) // default:'something'  like:default:'false' should be between quotes (what AddToVars do)
}

func handleDefaultValue(scope *Scope, field *Field) string {
	if field.IsBlank {
		defaultValue := strings.TrimSpace(parseTagSetting(field.Tag.Get("sql"))["DEFAULT"])
		switch field.Field.Kind() {
		case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
			if numericValue, err := strconv.ParseInt(defaultValue, 10, 64); err == nil {
				if numericValue != field.Field.Int() {
					return escapeIfNeeded(scope, fmt.Sprintf("%d", field.Field.Int()))
				} else {
					return escapeIfNeeded(scope, defaultValue)
				}
			}
		case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
			if numericValue, err := strconv.ParseUint(defaultValue, 10, 64); err == nil {
				if numericValue != field.Field.Uint() {
					return escapeIfNeeded(scope, escapeIfNeeded(scope, fmt.Sprintf("%d", field.Field.Int())))
				} else {
					return escapeIfNeeded(scope, defaultValue)
				}
			}
		case reflect.Bool:
			if boolValue, err := strconv.ParseBool(defaultValue); err == nil {
				if boolValue != field.Field.Bool() {
					return escapeIfNeeded(scope, fmt.Sprintf("%t", field.Field.Bool()))
				} else {
					return escapeIfNeeded(scope, defaultValue)
				}
			}
			/*
				case reflect.String:
					if defaultValue != field.Field.String() {
						return escapeIfNeeded(scope, fmt.Sprintf("%s", field.Field.String()))
					} else {
						return escapeIfNeeded(scope, defaultValue)
					}
			*/
		default:
			return escapeIfNeeded(scope, defaultValue)
		}
	}
	return scope.AddToVars(field.Field.Interface())
}

var DefaultCallback = &callback{processors: []*callbackProcessor{}}