package processor

import (
	"fmt"
	"log"
	"modify/processor/xpath"
	"strings"

	"github.com/antchfx/xmlquery"
	lua "github.com/yuin/gopher-lua"
)

// XMLProcessor implements the Processor interface for XML documents
type XMLProcessor struct{}

// ProcessContent implements the Processor interface for XMLProcessor
func (p *XMLProcessor) ProcessContent(content string, path string, luaExpr string) (string, int, int, error) {
	// Parse XML document
	// We can't really use encoding/xml here because it requires a pre defined struct
	// And we HAVE TO parse dynamic unknown XML
	doc, err := xmlquery.Parse(strings.NewReader(content))
	if err != nil {
		return content, 0, 0, fmt.Errorf("error parsing XML: %v", err)
	}

	// Find nodes matching the XPath pattern
	nodes, err := xpath.Get(doc, path)
	if err != nil {
		return content, 0, 0, fmt.Errorf("error executing XPath: %v", err)
	}

	matchCount := len(nodes)
	if matchCount == 0 {
		return content, 0, 0, nil
	}

	// Apply modifications to each node
	modCount := 0
	for _, node := range nodes {
		L, err := NewLuaState()
		if err != nil {
			return content, 0, 0, fmt.Errorf("error creating Lua state: %v", err)
		}
		defer L.Close()

		err = p.ToLua(L, node)
		if err != nil {
			return content, modCount, matchCount, fmt.Errorf("error converting to Lua: %v", err)
		}

		err = L.DoString(BuildLuaScript(luaExpr))
		if err != nil {
			return content, modCount, matchCount, fmt.Errorf("error executing Lua: %v", err)
		}

		result, err := p.FromLua(L)
		if err != nil {
			return content, modCount, matchCount, fmt.Errorf("error getting result from Lua: %v", err)
		}
		log.Printf("%#v", result)

		modified := false
		modified = L.GetGlobal("modified").String() == "true"
		if !modified {
			log.Printf("No changes made to node at path: %s", node.Data)
			continue
		}

		// Apply modification based on the result
		if updatedValue, ok := result.(string); ok {
			// If the result is a simple string, update the node value directly
			xpath.Set(doc, path, updatedValue)
		} else if nodeData, ok := result.(map[string]interface{}); ok {
			// If the result is a map, apply more complex updates
			updateNodeFromMap(node, nodeData)
		}

		modCount++
	}

	// Serialize the modified XML document to string
	if doc.FirstChild != nil && doc.FirstChild.Type == xmlquery.DeclarationNode {
		// If we have an XML declaration, start with it
		declaration := doc.FirstChild.OutputXML(true)
		// Remove the firstChild (declaration) before serializing the rest of the document
		doc.FirstChild = doc.FirstChild.NextSibling
		return ConvertToNamedEntities(declaration + doc.OutputXML(true)), modCount, matchCount, nil
	}

	// Convert numeric entities to named entities for better readability
	return ConvertToNamedEntities(doc.OutputXML(true)), modCount, matchCount, nil
}

// ToLua converts XML node values to Lua variables
func (p *XMLProcessor) ToLua(L *lua.LState, data interface{}) error {
	// Check if data is an xmlquery.Node
	node, ok := data.(*xmlquery.Node)
	if !ok {
		return fmt.Errorf("expected xmlquery.Node, got %T", data)
	}

	// Create a simple table with essential data
	table := L.NewTable()

	// For element nodes, just provide basic info
	L.SetField(table, "type", lua.LString(nodeTypeToString(node.Type)))
	L.SetField(table, "name", lua.LString(node.Data))
	L.SetField(table, "value", lua.LString(node.InnerText()))

	// Add attributes if any
	if len(node.Attr) > 0 {
		attrs := L.NewTable()
		for _, attr := range node.Attr {
			L.SetField(attrs, attr.Name.Local, lua.LString(attr.Value))
		}
		L.SetField(table, "attr", attrs)
	}

	L.SetGlobal("v", table)
	return nil
}

// FromLua gets modified values from Lua
func (p *XMLProcessor) FromLua(L *lua.LState) (interface{}, error) {
	luaValue := L.GetGlobal("v")

	// Handle string values directly
	if luaValue.Type() == lua.LTString {
		return luaValue.String(), nil
	}

	// Handle tables (for attributes and more complex updates)
	if luaValue.Type() == lua.LTTable {
		return luaTableToMap(L, luaValue.(*lua.LTable)), nil
	}

	return luaValue.String(), nil
}

// Simple helper to convert a Lua table to a Go map
func luaTableToMap(L *lua.LState, table *lua.LTable) map[string]interface{} {
	result := make(map[string]interface{})

	table.ForEach(func(k, v lua.LValue) {
		if k.Type() == lua.LTString {
			key := k.String()

			if v.Type() == lua.LTTable {
				result[key] = luaTableToMap(L, v.(*lua.LTable))
			} else {
				result[key] = v.String()
			}
		}
	})

	return result
}

// Simple helper to convert node type to string
func nodeTypeToString(nodeType xmlquery.NodeType) string {
	switch nodeType {
	case xmlquery.ElementNode:
		return "element"
	case xmlquery.TextNode:
		return "text"
	case xmlquery.AttributeNode:
		return "attribute"
	default:
		return "other"
	}
}

// Helper function to update an XML node from a map
func updateNodeFromMap(node *xmlquery.Node, data map[string]interface{}) {
	// Update node value if present
	if value, ok := data["value"]; ok {
		if strValue, ok := value.(string); ok {
			// For element nodes, replace text content
			if node.Type == xmlquery.ElementNode {
				// Find the first text child if it exists
				var textNode *xmlquery.Node
				for child := node.FirstChild; child != nil; child = child.NextSibling {
					if child.Type == xmlquery.TextNode {
						textNode = child
						break
					}
				}

				if textNode != nil {
					// Update existing text node
					textNode.Data = strValue
				} else {
					// Create new text node
					newText := &xmlquery.Node{
						Type:   xmlquery.TextNode,
						Data:   strValue,
						Parent: node,
					}

					// Insert at beginning of children
					if node.FirstChild != nil {
						newText.NextSibling = node.FirstChild
						node.FirstChild.PrevSibling = newText
						node.FirstChild = newText
					} else {
						node.FirstChild = newText
						node.LastChild = newText
					}
				}
			} else if node.Type == xmlquery.TextNode {
				// Directly update text node
				node.Data = strValue
			} else if node.Type == xmlquery.AttributeNode {
				// Update attribute value
				if node.Parent != nil {
					for i, attr := range node.Parent.Attr {
						if attr.Name.Local == node.Data {
							node.Parent.Attr[i].Value = strValue
							break
						}
					}
				}
			}
		}
	}

	// Update attributes if present
	if attrs, ok := data["attr"].(map[string]interface{}); ok && node.Type == xmlquery.ElementNode {
		for name, value := range attrs {
			if strValue, ok := value.(string); ok {
				// Look for existing attribute
				found := false
				for i, attr := range node.Attr {
					if attr.Name.Local == name {
						node.Attr[i].Value = strValue
						found = true
						break
					}
				}

				// Add new attribute if not found
				if !found {
					node.Attr = append(node.Attr, xmlquery.Attr{
						Name: struct {
							Space, Local string
						}{Local: name},
						Value: strValue,
					})
				}
			}
		}
	}
}

// Helper function to get a string representation of node type
func nodeTypeName(nodeType xmlquery.NodeType) string {
	switch nodeType {
	case xmlquery.ElementNode:
		return "element"
	case xmlquery.TextNode:
		return "text"
	case xmlquery.AttributeNode:
		return "attribute"
	case xmlquery.CommentNode:
		return "comment"
	case xmlquery.DeclarationNode:
		return "declaration"
	default:
		return "unknown"
	}
}

// ConvertToNamedEntities replaces numeric XML entities with their named counterparts
func ConvertToNamedEntities(xml string) string {
	// Basic XML entities
	replacements := map[string]string{
		// Basic XML entities
		""": """, // double quote
		"'": "'", // single quote
		"<": "<",   // less than
		">": ">",   // greater than
		"&": "&",  // ampersand

		// Common symbols
		" ":  " ",   // non-breaking space
		"©":  "©",   // copyright
		"®":  "®",    // registered trademark
		"€": "€",   // euro
		"£":  "£",  // pound
		"¥":  "¥",    // yen
		"¢":  "¢",   // cent
		"§":  "§",   // section
		"™": "™",  // trademark
		"♠": "♠", // spade
		"♣": "♣",  // club
		"♥": "♥", // heart
		"♦": "♦",  // diamond

		// Special characters
		"¡":  "¡",  // inverted exclamation
		"¿":  "¿", // inverted question
		"«":  "«",  // left angle quotes
		"»":  "»",  // right angle quotes
		"·":  "·", // middle dot
		"•": "•",   // bullet
		"…": "…", // horizontal ellipsis
		"′": "′",  // prime
		"″": "″",  // double prime
		"‾": "‾",  // overline
		"⁄": "⁄",  // fraction slash

		// Math symbols
		"±":  "±", // plus-minus
		"×":  "×",  // multiplication
		"÷":  "÷", // division
		"∞": "∞",  // infinity
		"≈": "≈",  // almost equal
		"≠": "≠",     // not equal
		"≤": "≤",     // less than or equal
		"≥": "≥",     // greater than or equal
		"∑": "∑",    // summation
		"√": "√",  // square root
		"∫": "∫",    // integral

		// Accented characters
		"À": "À", // A grave
		"Á": "Á", // A acute
		"Â": "Â",  // A circumflex
		"Ã": "Ã", // A tilde
		"Ä": "Ä",   // A umlaut
		"Å": "Å",  // A ring
		"Æ": "Æ",  // AE ligature
		"Ç": "Ç", // C cedilla
		"È": "È", // E grave
		"É": "É", // E acute
		"Ê": "Ê",  // E circumflex
		"Ë": "Ë",   // E umlaut
		"Ì": "Ì", // I grave
		"Í": "Í", // I acute
		"Î": "Î",  // I circumflex
		"Ï": "Ï",   // I umlaut
		"Ð": "Ð",    // Eth
		"Ñ": "Ñ", // N tilde
		"Ò": "Ò", // O grave
		"Ó": "Ó", // O acute
		"Ô": "Ô",  // O circumflex
		"Õ": "Õ", // O tilde
		"Ö": "Ö",   // O umlaut
		"Ø": "Ø", // O slash
		"Ù": "Ù", // U grave
		"Ú": "Ú", // U acute
		"Û": "Û",  // U circumflex
		"Ü": "Ü",   // U umlaut
		"Ý": "Ý", // Y acute
		"Þ": "Þ",  // Thorn
		"ß": "ß",  // Sharp s
		"à": "à", // a grave
		"á": "á", // a acute
		"â": "â",  // a circumflex
		"ã": "ã", // a tilde
		"ä": "ä",   // a umlaut
		"å": "å",  // a ring
		"æ": "æ",  // ae ligature
		"ç": "ç", // c cedilla
		"è": "è", // e grave
		"é": "é", // e acute
		"ê": "ê",  // e circumflex
		"ë": "ë",   // e umlaut
		"ì": "ì", // i grave
		"í": "í", // i acute
		"î": "î",  // i circumflex
		"ï": "ï",   // i umlaut
		"ð": "ð",    // eth
		"ñ": "ñ", // n tilde
		"ò": "ò", // o grave
		"ó": "ó", // o acute
		"ô": "ô",  // o circumflex
		"õ": "õ", // o tilde
		"ö": "ö",   // o umlaut
		"ø": "ø", // o slash
		"ù": "ù", // u grave
		"ú": "ú", // u acute
		"û": "û",  // u circumflex
		"ü": "ü",   // u umlaut
		"ý": "ý", // y acute
		"þ": "þ",  // thorn
		"ÿ": "ÿ",   // y umlaut
	}

	result := xml
	for numeric, named := range replacements {
		result = strings.ReplaceAll(result, numeric, named)
	}
	return result
}