package processor

import (
	"encoding/json"
	"fmt"
	"os"
	"path/filepath"
	"regexp"
	"strconv"
	"strings"

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

// JSONProcessor implements the Processor interface using JSONPath
type JSONProcessor struct {
	Logger Logger
}

// NewJSONProcessor creates a new JSONProcessor
func NewJSONProcessor(logger Logger) *JSONProcessor {
	return &JSONProcessor{
		Logger: logger,
	}
}

// Process implements the Processor interface for JSONProcessor
func (p *JSONProcessor) Process(filename string, pattern string, luaExpr string, originalExpr string) (int, int, error) {
	// Use pattern as JSONPath expression
	jsonPathExpr := pattern

	// Read file content
	fullPath := filepath.Join(".", filename)
	content, err := os.ReadFile(fullPath)
	if err != nil {
		return 0, 0, fmt.Errorf("error reading file: %v", err)
	}

	fileContent := string(content)
	if p.Logger != nil {
		p.Logger.Printf("File %s loaded: %d bytes", fullPath, len(content))
	}

	// Process the content
	modifiedContent, modCount, matchCount, err := p.ProcessContent(fileContent, jsonPathExpr, luaExpr, originalExpr)
	if err != nil {
		return 0, 0, err
	}

	// If we made modifications, save the file
	if modCount > 0 {
		err = os.WriteFile(fullPath, []byte(modifiedContent), 0644)
		if err != nil {
			return 0, 0, fmt.Errorf("error writing file: %v", err)
		}

		if p.Logger != nil {
			p.Logger.Printf("Made %d JSON value modifications to %s and saved (%d bytes)",
				modCount, fullPath, len(modifiedContent))
		}
	} else if p.Logger != nil {
		p.Logger.Printf("No modifications made to %s", fullPath)
	}

	return modCount, matchCount, nil
}

// ToLua implements the Processor interface for JSONProcessor
func (p *JSONProcessor) ToLua(L *lua.LState, data interface{}) error {
	// For JSON, convert different types to appropriate Lua types
	return nil
}

// FromLua implements the Processor interface for JSONProcessor
func (p *JSONProcessor) FromLua(L *lua.LState) (interface{}, error) {
	// Extract changes from Lua environment
	return nil, nil
}

// ProcessContent implements the Processor interface for JSONProcessor
// It processes JSON content directly without file I/O
func (p *JSONProcessor) ProcessContent(content string, pattern string, luaExpr string, originalExpr string) (string, int, int, error) {
	// Parse JSON
	var jsonDoc interface{}
	err := json.Unmarshal([]byte(content), &jsonDoc)
	if err != nil {
		return "", 0, 0, fmt.Errorf("error parsing JSON: %v", err)
	}

	// Log the JSONPath expression we're using
	if p.Logger != nil {
		p.Logger.Printf("JSON mode selected with JSONPath expression: %s", pattern)
	}

	// Initialize Lua state
	L := lua.NewState()
	defer L.Close()

	// Setup Lua helper functions
	if err := InitLuaHelpers(L); err != nil {
		return "", 0, 0, err
	}

	// Setup JSON helpers
	p.SetupJSONHelpers(L)

	// Find matching nodes with simple JSONPath implementation
	matchingPaths, err := p.findNodePaths(jsonDoc, pattern)
	if err != nil {
		return "", 0, 0, fmt.Errorf("error finding JSON nodes: %v", err)
	}

	if len(matchingPaths) == 0 {
		if p.Logger != nil {
			p.Logger.Printf("No JSON nodes matched JSONPath expression: %s", pattern)
		}
		return content, 0, 0, nil
	}

	if p.Logger != nil {
		p.Logger.Printf("Found %d JSON nodes matching the path", len(matchingPaths))
	}

	// Process each node
	matchCount := len(matchingPaths)
	modificationCount := 0
	modifications := []ModificationRecord{}

	// Clone the document for modification
	var modifiedDoc interface{}
	modifiedBytes, err := json.Marshal(jsonDoc)
	if err != nil {
		return "", 0, 0, fmt.Errorf("error cloning JSON document: %v", err)
	}

	err = json.Unmarshal(modifiedBytes, &modifiedDoc)
	if err != nil {
		return "", 0, 0, fmt.Errorf("error cloning JSON document: %v", err)
	}

	// For each matching path, extract value, apply Lua script, and update
	for i, path := range matchingPaths {
		// Extract the original value
		originalValue, err := p.getValueAtPath(jsonDoc, path)
		if err != nil || originalValue == nil {
			if p.Logger != nil {
				p.Logger.Printf("Error getting value at path %v: %v", path, err)
			}
			continue
		}

		if p.Logger != nil {
			p.Logger.Printf("Processing node #%d at path %v with value: %v", i+1, path, originalValue)
		}

		// Process based on the value type
		switch val := originalValue.(type) {
		case float64:
			// Set up Lua environment for numeric value
			L.SetGlobal("v1", lua.LNumber(val))
			L.SetGlobal("s1", lua.LString(fmt.Sprintf("%v", val)))

			// Execute Lua script
			if err := L.DoString(luaExpr); err != nil {
				if p.Logger != nil {
					p.Logger.Printf("Lua execution failed for node #%d: %v", i+1, err)
				}
				continue
			}

			// Extract modified value
			modVal := L.GetGlobal("v1")
			if v, ok := modVal.(lua.LNumber); ok {
				newValue := float64(v)

				// Update the value in the document only if it changed
				if newValue != val {
					err := p.setValueAtPath(modifiedDoc, path, newValue)
					if err != nil {
						if p.Logger != nil {
							p.Logger.Printf("Error updating value at path %v: %v", path, err)
						}
						continue
					}

					modificationCount++
					modifications = append(modifications, ModificationRecord{
						File:      "",
						OldValue:  fmt.Sprintf("%v", val),
						NewValue:  fmt.Sprintf("%v", newValue),
						Operation: originalExpr,
						Context:   fmt.Sprintf("(JSONPath: %s)", pattern),
					})

					if p.Logger != nil {
						p.Logger.Printf("Modified numeric node #%d: %v -> %v", i+1, val, newValue)
					}
				}
			}

		case string:
			// Set up Lua environment for string value
			L.SetGlobal("s1", lua.LString(val))

			// Try to convert to number if possible
			if floatVal, err := strconv.ParseFloat(val, 64); err == nil {
				L.SetGlobal("v1", lua.LNumber(floatVal))
			} else {
				L.SetGlobal("v1", lua.LNumber(0)) // Default to 0 if not numeric
			}

			// Execute Lua script
			if err := L.DoString(luaExpr); err != nil {
				if p.Logger != nil {
					p.Logger.Printf("Lua execution failed for node #%d: %v", i+1, err)
				}
				continue
			}

			// Check for modifications in string (s1) or numeric (v1) values
			var newValue interface{}
			modified := false

			// Check if s1 was modified
			sVal := L.GetGlobal("s1")
			if s, ok := sVal.(lua.LString); ok && string(s) != val {
				newValue = string(s)
				modified = true
			} else {
				// Check if v1 was modified to a number
				vVal := L.GetGlobal("v1")
				if v, ok := vVal.(lua.LNumber); ok {
					numStr := strconv.FormatFloat(float64(v), 'f', -1, 64)
					if numStr != val {
						newValue = numStr
						modified = true
					}
				}
			}

			// Apply the modification if anything changed
			if modified {
				err := p.setValueAtPath(modifiedDoc, path, newValue)
				if err != nil {
					if p.Logger != nil {
						p.Logger.Printf("Error updating value at path %v: %v", path, err)
					}
					continue
				}

				modificationCount++
				modifications = append(modifications, ModificationRecord{
					File:      "",
					OldValue:  val,
					NewValue:  fmt.Sprintf("%v", newValue),
					Operation: originalExpr,
					Context:   fmt.Sprintf("(JSONPath: %s)", pattern),
				})

				if p.Logger != nil {
					p.Logger.Printf("Modified string node #%d: '%s' -> '%s'",
						i+1, LimitString(val, 30), LimitString(fmt.Sprintf("%v", newValue), 30))
				}
			}
		}
	}

	// Marshal the modified document back to JSON with indentation
	if modificationCount > 0 {
		modifiedJSON, err := json.MarshalIndent(modifiedDoc, "", "  ")
		if err != nil {
			return "", 0, 0, fmt.Errorf("error marshaling modified JSON: %v", err)
		}

		if p.Logger != nil {
			p.Logger.Printf("Made %d JSON node modifications", modificationCount)
		}

		return string(modifiedJSON), modificationCount, matchCount, nil
	}

	// If no modifications were made, return the original content
	return content, 0, matchCount, nil
}

// findNodePaths implements a simplified JSONPath for finding paths to nodes
func (p *JSONProcessor) findNodePaths(doc interface{}, path string) ([][]interface{}, error) {
	// Validate the path has proper syntax
	if strings.Contains(path, "[[") || strings.Contains(path, "]]") {
		return nil, fmt.Errorf("invalid JSONPath syntax: %s", path)
	}

	// Handle root element special case
	if path == "$" {
		return [][]interface{}{{doc}}, nil
	}

	// Split path into segments
	segments := strings.Split(strings.TrimPrefix(path, "$."), ".")

	// Start with the root
	current := [][]interface{}{{doc}}

	// Process each segment
	for _, segment := range segments {
		var next [][]interface{}

		// Handle array notation [*]
		if segment == "[*]" || strings.HasSuffix(segment, "[*]") {
			baseName := strings.TrimSuffix(segment, "[*]")

			for _, path := range current {
				item := path[len(path)-1] // Get the last item in the path

				switch v := item.(type) {
				case map[string]interface{}:
					if baseName == "" {
						// [*] means all elements at this level
						for _, val := range v {
							if arr, ok := val.([]interface{}); ok {
								for i, elem := range arr {
									newPath := make([]interface{}, len(path)+2)
									copy(newPath, path)
									newPath[len(path)] = i // Array index
									newPath[len(path)+1] = elem
									next = append(next, newPath)
								}
							}
						}
					} else if arr, ok := v[baseName].([]interface{}); ok {
						for i, elem := range arr {
							newPath := make([]interface{}, len(path)+3)
							copy(newPath, path)
							newPath[len(path)] = baseName
							newPath[len(path)+1] = i // Array index
							newPath[len(path)+2] = elem
							next = append(next, newPath)
						}
					}
				case []interface{}:
					for i, elem := range v {
						newPath := make([]interface{}, len(path)+1)
						copy(newPath, path)
						newPath[len(path)-1] = i // Replace last elem with index
						newPath[len(path)] = elem
						next = append(next, newPath)
					}
				}
			}

			current = next
			continue
		}

		// Handle specific array indices
		if strings.Contains(segment, "[") && strings.Contains(segment, "]") {
			// Validate proper array syntax
			if !regexp.MustCompile(`\[\d+\]$`).MatchString(segment) {
				return nil, fmt.Errorf("invalid array index in JSONPath: %s", segment)
			}

			// Extract base name and index
			baseName := segment[:strings.Index(segment, "[")]
			idxStr := segment[strings.Index(segment, "[")+1 : strings.Index(segment, "]")]
			idx, err := strconv.Atoi(idxStr)
			if err != nil {
				return nil, fmt.Errorf("invalid array index: %s", idxStr)
			}

			for _, path := range current {
				item := path[len(path)-1] // Get the last item in the path

				if obj, ok := item.(map[string]interface{}); ok {
					if arr, ok := obj[baseName].([]interface{}); ok && idx < len(arr) {
						newPath := make([]interface{}, len(path)+3)
						copy(newPath, path)
						newPath[len(path)] = baseName
						newPath[len(path)+1] = idx
						newPath[len(path)+2] = arr[idx]
						next = append(next, newPath)
					}
				}
			}

			current = next
			continue
		}

		// Handle regular object properties
		for _, path := range current {
			item := path[len(path)-1] // Get the last item in the path

			if obj, ok := item.(map[string]interface{}); ok {
				if val, exists := obj[segment]; exists {
					newPath := make([]interface{}, len(path)+2)
					copy(newPath, path)
					newPath[len(path)] = segment
					newPath[len(path)+1] = val
					next = append(next, newPath)
				}
			}
		}

		current = next
	}

	return current, nil
}

// getValueAtPath extracts a value from a JSON document at the specified path
func (p *JSONProcessor) getValueAtPath(doc interface{}, path []interface{}) (interface{}, error) {
	if len(path) == 0 {
		return nil, fmt.Errorf("empty path")
	}

	// The last element in the path is the value itself
	return path[len(path)-1], nil
}

// setValueAtPath updates a value in a JSON document at the specified path
func (p *JSONProcessor) setValueAtPath(doc interface{}, path []interface{}, newValue interface{}) error {
	if len(path) < 2 {
		return fmt.Errorf("path too short to update value")
	}

	// The path structure alternates: object/key/object/key/.../finalObject/finalKey/value
	// We need to navigate to the object containing our key
	// We'll get the parent object and the key to modify

	// Find the parent object (second to last object) and the key (last object's property name)
	// For the path structure, the parent is at index len-3 and key at len-2
	if len(path) < 3 {
		// Simple case: directly update the root object
		rootObj, ok := doc.(map[string]interface{})
		if !ok {
			return fmt.Errorf("root is not an object, cannot update")
		}

		// Key should be a string
		key, ok := path[len(path)-2].(string)
		if !ok {
			return fmt.Errorf("key is not a string: %v", path[len(path)-2])
		}

		rootObj[key] = newValue
		return nil
	}

	// More complex case: we need to navigate to the parent object
	parentIdx := len(path) - 3
	keyIdx := len(path) - 2

	// The actual key we need to modify
	key, isString := path[keyIdx].(string)
	keyInt, isInt := path[keyIdx].(int)

	if !isString && !isInt {
		return fmt.Errorf("key must be string or int, got %T", path[keyIdx])
	}

	// Get the parent object that contains the key
	parent := path[parentIdx]

	// If parent is a map, use string key
	if parentMap, ok := parent.(map[string]interface{}); ok && isString {
		parentMap[key] = newValue
		return nil
	}

	// If parent is an array, use int key
	if parentArray, ok := parent.([]interface{}); ok && isInt {
		if keyInt < 0 || keyInt >= len(parentArray) {
			return fmt.Errorf("array index %d out of bounds [0,%d)", keyInt, len(parentArray))
		}
		parentArray[keyInt] = newValue
		return nil
	}

	return fmt.Errorf("cannot update value: parent is %T and key is %T", parent, path[keyIdx])
}

// SetupJSONHelpers adds JSON-specific helper functions to Lua
func (p *JSONProcessor) SetupJSONHelpers(L *lua.LState) {
	// Helper to get type of JSON value
	L.SetGlobal("json_type", L.NewFunction(func(L *lua.LState) int {
		// Get the value passed to the function
		val := L.Get(1)

		// Determine type
		switch val.Type() {
		case lua.LTNil:
			L.Push(lua.LString("null"))
		case lua.LTBool:
			L.Push(lua.LString("boolean"))
		case lua.LTNumber:
			L.Push(lua.LString("number"))
		case lua.LTString:
			L.Push(lua.LString("string"))
		case lua.LTTable:
			// Could be object or array - check for numeric keys
			isArray := true
			table := val.(*lua.LTable)
			table.ForEach(func(key, value lua.LValue) {
				if key.Type() != lua.LTNumber {
					isArray = false
				}
			})

			if isArray {
				L.Push(lua.LString("array"))
			} else {
				L.Push(lua.LString("object"))
			}
		default:
			L.Push(lua.LString("unknown"))
		}

		return 1
	}))
}

// jsonToLua converts a Go JSON value to a Lua value
func (p *JSONProcessor) jsonToLua(L *lua.LState, val interface{}) lua.LValue {
	if val == nil {
		return lua.LNil
	}

	switch v := val.(type) {
	case bool:
		return lua.LBool(v)
	case float64:
		return lua.LNumber(v)
	case string:
		return lua.LString(v)
	case []interface{}:
		arr := L.NewTable()
		for i, item := range v {
			arr.RawSetInt(i+1, p.jsonToLua(L, item))
		}
		return arr
	case map[string]interface{}:
		obj := L.NewTable()
		for k, item := range v {
			obj.RawSetString(k, p.jsonToLua(L, item))
		}
		return obj
	default:
		// For unknown types, convert to string representation
		return lua.LString(fmt.Sprintf("%v", val))
	}
}

// luaToJSON converts a Lua value to a Go JSON-compatible value
func (p *JSONProcessor) luaToJSON(val lua.LValue) interface{} {
	switch val.Type() {
	case lua.LTNil:
		return nil
	case lua.LTBool:
		return lua.LVAsBool(val)
	case lua.LTNumber:
		return float64(val.(lua.LNumber))
	case lua.LTString:
		return val.String()
	case lua.LTTable:
		table := val.(*lua.LTable)

		// Check if it's an array or an object
		isArray := true
		maxN := 0

		table.ForEach(func(key, _ lua.LValue) {
			if key.Type() == lua.LTNumber {
				n := int(key.(lua.LNumber))
				if n > maxN {
					maxN = n
				}
			} else {
				isArray = false
			}
		})

		if isArray && maxN > 0 {
			// It's an array
			arr := make([]interface{}, maxN)
			for i := 1; i <= maxN; i++ {
				item := table.RawGetInt(i)
				if item != lua.LNil {
					arr[i-1] = p.luaToJSON(item)
				}
			}
			return arr
		} else {
			// It's an object
			obj := make(map[string]interface{})
			table.ForEach(func(key, value lua.LValue) {
				if key.Type() == lua.LTString {
					obj[key.String()] = p.luaToJSON(value)
				} else {
					// Convert key to string if it's not already
					obj[fmt.Sprintf("%v", key)] = p.luaToJSON(value)
				}
			})
			return obj
		}
	default:
		// For functions, userdata, etc., convert to string
		return val.String()
	}
}