// Package processor provides JSON processing and Lua script execution capabilities
// for data transformation and manipulation.
package processor

import (
	"cook/utils"
	"encoding/json"
	"fmt"
	"sort"
	"strconv"
	"strings"
	"time"

	logger "git.site.quack-lab.dev/dave/cylogger"
	"github.com/tidwall/gjson"
	lua "github.com/yuin/gopher-lua"
)

// jsonLogger is a scoped logger for the processor/json package.
var jsonLogger = logger.Default.WithPrefix("processor/json")

// ProcessJSON applies Lua processing to JSON content
func ProcessJSON(content string, command utils.ModifyCommand, filename string) ([]utils.ReplaceCommand, error) {
	processJSONLogger := jsonLogger.WithPrefix("ProcessJSON").WithField("commandName", command.Name).WithField("file", filename)
	processJSONLogger.Debug("Starting JSON processing for file")
	processJSONLogger.Trace("Initial file content length: %d", len(content))

	var commands []utils.ReplaceCommand
	startTime := time.Now()

	// Parse JSON content
	var jsonData interface{}
	err := json.Unmarshal([]byte(content), &jsonData)
	if err != nil {
		processJSONLogger.Error("Failed to parse JSON content: %v", err)
		return commands, fmt.Errorf("failed to parse JSON: %v", err)
	}
	processJSONLogger.Debug("Successfully parsed JSON content")

	// Create Lua state
	L, err := NewLuaState()
	if err != nil {
		processJSONLogger.Error("Error creating Lua state: %v", err)
		return commands, fmt.Errorf("error creating Lua state: %v", err)
	}
	defer L.Close()

	// Set filename global
	L.SetGlobal("file", lua.LString(filename))

	// Convert JSON data to Lua table
	luaTable, err := ToLuaTable(L, jsonData)
	if err != nil {
		processJSONLogger.Error("Failed to convert JSON to Lua table: %v", err)
		return commands, fmt.Errorf("failed to convert JSON to Lua table: %v", err)
	}

	// Set the JSON data as a global variable
	L.SetGlobal("data", luaTable)
	processJSONLogger.Debug("Set JSON data as Lua global 'data'")

	// Build and execute Lua script for JSON mode
	luaExpr := BuildJSONLuaScript(command.Lua, command.SourceDir)
	processJSONLogger.Debug("Built Lua script from expression: %q", command.Lua)
	processJSONLogger.Trace("Full Lua script: %q", utils.LimitString(luaExpr, 200))

	if err := L.DoString(luaExpr); err != nil {
		processJSONLogger.Error("Lua script execution failed: %v\nScript: %s", err, utils.LimitString(luaExpr, 200))
		return commands, fmt.Errorf("lua script execution failed: %v", err)
	}
	processJSONLogger.Debug("Lua script executed successfully")

	// Check if modification flag is set
	modifiedVal := L.GetGlobal("modified")
	if modifiedVal.Type() != lua.LTBool || !lua.LVAsBool(modifiedVal) {
		processJSONLogger.Debug("Skipping - no modifications indicated by Lua script")
		return commands, nil
	}

	// Get the modified data from Lua
	modifiedData := L.GetGlobal("data")
	if modifiedData.Type() != lua.LTTable {
		processJSONLogger.Error("Expected 'data' to be a table after Lua processing, got %s", modifiedData.Type().String())
		return commands, fmt.Errorf("expected 'data' to be a table after Lua processing")
	}

	// Convert back to Go interface
	goData, err := FromLua(L, modifiedData)
	if err != nil {
		processJSONLogger.Error("Failed to convert Lua table back to Go: %v", err)
		return commands, fmt.Errorf("failed to convert Lua table back to Go: %v", err)
	}

	processJSONLogger.Debug("About to call applyChanges with original data and modified data")
	commands, err = applyChanges(content, jsonData, goData)
	if err != nil {
		processJSONLogger.Error("Failed to apply surgical JSON changes: %v", err)
		return commands, fmt.Errorf("failed to apply surgical JSON changes: %v", err)
	}

	processJSONLogger.Debug("Total JSON processing time: %v", time.Since(startTime))
	processJSONLogger.Debug("Generated %d total modifications", len(commands))
	return commands, nil
}

// applyChanges attempts to make surgical changes while preserving exact formatting
func applyChanges(content string, originalData, modifiedData interface{}) ([]utils.ReplaceCommand, error) {
	var commands []utils.ReplaceCommand

	// Find all changes between original and modified data
	changes := findDeepChanges("", originalData, modifiedData)

	jsonLogger.Debug("applyChanges: Found %d changes: %v", len(changes), changes)

	if len(changes) == 0 {
		return commands, nil
	}

	// Sort removal operations by index in descending order to avoid index shifting
	var removals []string
	var additions []string
	var valueChanges []string

	for path := range changes {
		if strings.HasSuffix(path, "@remove") {
			removals = append(removals, path)
		} else if strings.HasSuffix(path, "@add") {
			additions = append(additions, path)
		} else {
			valueChanges = append(valueChanges, path)
		}
	}

	jsonLogger.Debug("applyChanges: %d removals, %d additions, %d value changes", len(removals), len(additions), len(valueChanges))

	// Apply removals first (from end to beginning to avoid index shifting)
	for _, removalPath := range removals {
		actualPath := strings.TrimSuffix(removalPath, "@remove")
		elementIndex := extractIndexFromRemovalPath(actualPath)
		arrayPath := getArrayPathFromElementPath(actualPath)

		jsonLogger.Debug("Processing removal: path=%s, index=%d, arrayPath=%s", actualPath, elementIndex, arrayPath)

		// Find the exact byte range to remove
		from, to := findArrayElementRemovalRange(content, arrayPath, elementIndex)

		jsonLogger.Debug("Removing bytes %d-%d", from, to)

		commands = append(commands, utils.ReplaceCommand{
			From: from,
			To:   to,
			With: "",
		})

		jsonLogger.Debug("Added removal command: From=%d, To=%d, With=\"\"", from, to)
	}

	// Apply additions (new fields)
	for _, additionPath := range additions {
		actualPath := strings.TrimSuffix(additionPath, "@add")
		newValue := changes[additionPath]

		jsonLogger.Debug("Processing addition: path=%s, value=%v", actualPath, newValue)

		// Find the parent object to add the field to
		parentPath := getParentPath(actualPath)
		fieldName := getFieldName(actualPath)

		jsonLogger.Debug("Parent path: %s, field name: %s", parentPath, fieldName)

		// Get the parent object
		var parentResult gjson.Result
		if parentPath == "" {
			// Adding to root object - get the entire JSON
			parentResult = gjson.Parse(content)
		} else {
			parentResult = gjson.Get(content, parentPath)
		}

		if !parentResult.Exists() {
			jsonLogger.Debug("Parent path %s does not exist, skipping", parentPath)
			continue
		}

		// Find where to insert the new field (at the end of the object)
		startPos := int(parentResult.Index + len(parentResult.Raw) - 1) // Before closing brace

		jsonLogger.Debug("Inserting at pos %d", startPos)

		// Convert the new value to JSON string
		newValueStr := convertValueToJSONString(newValue)

		// Insert the new field with pretty-printed formatting
		// Format: ,"fieldName": { ... }
		insertText := fmt.Sprintf(`,"%s": %s`, fieldName, newValueStr)

		commands = append(commands, utils.ReplaceCommand{
			From: startPos,
			To:   startPos,
			With: insertText,
		})

		jsonLogger.Debug("Added addition command: From=%d, To=%d, With=%q", startPos, startPos, insertText)
	}

	// Apply value changes (in reverse order to avoid position shifting)
	sort.Slice(valueChanges, func(i, j int) bool {
		// Get positions for comparison
		resultI := gjson.Get(content, valueChanges[i])
		resultJ := gjson.Get(content, valueChanges[j])
		return resultI.Index > resultJ.Index // Descending order
	})

	for _, path := range valueChanges {
		newValue := changes[path]

		jsonLogger.Debug("Processing value change: path=%s, value=%v", path, newValue)

		// Get the current value and its position in the original JSON
		result := gjson.Get(content, path)
		if !result.Exists() {
			jsonLogger.Debug("Path %s does not exist, skipping", path)
			continue // Skip if path doesn't exist
		}

		// Get the exact byte positions of this value
		startPos := result.Index
		endPos := startPos + len(result.Raw)

		jsonLogger.Debug("Found value at pos %d-%d: %q", startPos, endPos, result.Raw)

		// Convert the new value to JSON string
		newValueStr := convertValueToJSONString(newValue)

		jsonLogger.Debug("Converting to: %q", newValueStr)

		// Create a replacement command for this specific value
		commands = append(commands, utils.ReplaceCommand{
			From: int(startPos),
			To:   int(endPos),
			With: newValueStr,
		})

		jsonLogger.Debug("Added command: From=%d, To=%d, With=%q", int(startPos), int(endPos), newValueStr)
	}

	return commands, nil
}

// extractIndexFromRemovalPath extracts the array index from a removal path like "Rows.0.Inputs.1@remove"
func extractIndexFromRemovalPath(path string) int {
	parts := strings.Split(strings.TrimSuffix(path, "@remove"), ".")
	if len(parts) > 0 {
		lastPart := parts[len(parts)-1]
		if index, err := strconv.Atoi(lastPart); err == nil {
			return index
		}
	}
	return -1
}

// getArrayPathFromElementPath converts "Rows.0.Inputs.1" to "Rows.0.Inputs"
func getArrayPathFromElementPath(elementPath string) string {
	parts := strings.Split(elementPath, ".")
	if len(parts) > 0 {
		return strings.Join(parts[:len(parts)-1], ".")
	}
	return ""
}

// getParentPath extracts the parent path from a full path like "Rows.0.Inputs.1"
func getParentPath(fullPath string) string {
	parts := strings.Split(fullPath, ".")
	if len(parts) > 0 {
		return strings.Join(parts[:len(parts)-1], ".")
	}
	return ""
}

// getFieldName extracts the field name from a full path like "Rows.0.Inputs.1"
func getFieldName(fullPath string) string {
	parts := strings.Split(fullPath, ".")
	if len(parts) > 0 {
		return parts[len(parts)-1]
	}
	return ""
}

// convertValueToJSONString converts a Go interface{} to a JSON string representation
func convertValueToJSONString(value interface{}) string {
	switch v := value.(type) {
	case string:
		return `"` + strings.ReplaceAll(v, `"`, `\"`) + `"`
	case float64:
		if v == float64(int64(v)) {
			return strconv.FormatInt(int64(v), 10)
		}
		return strconv.FormatFloat(v, 'f', -1, 64)
	case bool:
		return strconv.FormatBool(v)
	case nil:
		return "null"
	case map[string]interface{}:
		// Handle maps specially to avoid double-escaping of keys
		var pairs []string
		for key, val := range v {
			// The key might already have escaped quotes from Lua, so we need to be careful
			// If the key already contains escaped quotes, we need to unescape them first
			keyStr := key
			if strings.Contains(key, `\"`) {
				// Key already has escaped quotes, use it as-is
				keyStr = `"` + key + `"`
			} else {
				// Normal key, escape quotes
				keyStr = `"` + strings.ReplaceAll(key, `"`, `\"`) + `"`
			}
			valStr := convertValueToJSONString(val)
			pairs = append(pairs, keyStr+":"+valStr)
		}
		return "{" + strings.Join(pairs, ",") + "}"
	default:
		// For other complex types (arrays), we need to use json.Marshal
		jsonBytes, err := json.Marshal(v)
		if err != nil {
			return "null" // Fallback to null if marshaling fails
		}
		return string(jsonBytes)
	}
}

// findArrayElementRemovalRange finds the exact byte range to remove for an array element
func findArrayElementRemovalRange(content, arrayPath string, elementIndex int) (int, int) {
	// Get the array using gjson
	var arrayResult gjson.Result
	if arrayPath == "" {
		// Root-level array
		arrayResult = gjson.Parse(content)
	} else {
		arrayResult = gjson.Get(content, arrayPath)
	}

	if !arrayResult.Exists() || !arrayResult.IsArray() {
		return -1, -1
	}

	// Get all array elements
	elements := arrayResult.Array()
	if elementIndex >= len(elements) {
		return -1, -1
	}

	// Get the target element
	elementResult := elements[elementIndex]
	startPos := int(elementResult.Index)
	endPos := int(elementResult.Index + len(elementResult.Raw))

	// Handle comma removal properly
	if elementIndex == 0 && len(elements) > 1 {
		// First element but not the only one - remove comma after
		for i := endPos; i < len(content) && i < endPos+50; i++ {
			if content[i] == ',' {
				endPos = i + 1
				break
			}
		}
	} else if elementIndex == len(elements)-1 && len(elements) > 1 {
		// Last element and not the only one - remove comma before
		prevElementEnd := int(elements[elementIndex-1].Index + len(elements[elementIndex-1].Raw))
		for i := prevElementEnd; i < startPos && i < len(content); i++ {
			if content[i] == ',' {
				startPos = i
				break
			}
		}
	}
	// If it's the only element, don't remove any commas

	return startPos, endPos
}

// findDeepChanges recursively finds all paths that need to be changed
func findDeepChanges(basePath string, original, modified interface{}) map[string]interface{} {
	changes := make(map[string]interface{})

	switch orig := original.(type) {
	case map[string]interface{}:
		if mod, ok := modified.(map[string]interface{}); ok {
			// Check for new keys added in modified data
			for key, modValue := range mod {
				var currentPath string
				if basePath == "" {
					currentPath = key
				} else {
					currentPath = basePath + "." + key
				}

				if origValue, exists := orig[key]; exists {
					// Key exists in both, check if value changed
					switch modValue.(type) {
					case map[string]interface{}, []interface{}:
						// Recursively check nested structures
						nestedChanges := findDeepChanges(currentPath, origValue, modValue)
						for nestedPath, nestedValue := range nestedChanges {
							changes[nestedPath] = nestedValue
						}
					default:
						// Primitive value - check if changed
						if !deepEqual(origValue, modValue) {
							changes[currentPath] = modValue
						}
					}
				} else {
					// New key added - mark for addition
					changes[currentPath+"@add"] = modValue
				}
			}
		}
	case []interface{}:
		if mod, ok := modified.([]interface{}); ok {
			// Handle array changes by detecting specific element operations
			if len(orig) != len(mod) {
				// Array length changed - detect if it's element removal
				if len(orig) > len(mod) {
					// Element(s) removed - find which ones by comparing content
					removedIndices := findRemovedArrayElements(orig, mod)
					for _, removedIndex := range removedIndices {
						var currentPath string
						if basePath == "" {
							currentPath = fmt.Sprintf("%d@remove", removedIndex)
						} else {
							currentPath = fmt.Sprintf("%s.%d@remove", basePath, removedIndex)
						}
						changes[currentPath] = nil // Mark for removal
					}
				}
			} else {
				// Same length - check individual elements for value changes
				for i, modValue := range mod {
					var currentPath string
					if basePath == "" {
						currentPath = strconv.Itoa(i)
					} else {
						currentPath = basePath + "." + strconv.Itoa(i)
					}

					if i < len(orig) {
						// Index exists in both, check if value changed
						switch modValue.(type) {
						case map[string]interface{}, []interface{}:
							// Recursively check nested structures
							nestedChanges := findDeepChanges(currentPath, orig[i], modValue)
							for nestedPath, nestedValue := range nestedChanges {
								changes[nestedPath] = nestedValue
							}
						default:
							// Primitive value - check if changed
							if !deepEqual(orig[i], modValue) {
								changes[currentPath] = modValue
							}
						}
					}
				}
			}
		}
	}
	// Note: No default case needed - JSON data from unmarshaling is always
	// map[string]interface{} or []interface{} at the top level

	return changes
}

// findRemovedArrayElements compares two arrays and returns indices of removed elements
func findRemovedArrayElements(original, modified []interface{}) []int {
	var removedIndices []int

	// Simple approach: find elements in original that don't exist in modified
	for i, origElement := range original {
		found := false
		for _, modElement := range modified {
			if deepEqual(origElement, modElement) {
				found = true
				break
			}
		}
		if !found {
			removedIndices = append(removedIndices, i)
		}
	}

	return removedIndices
}

// deepEqual performs deep comparison of two values
func deepEqual(a, b interface{}) bool {
	if a == nil && b == nil {
		return true
	}
	if a == nil || b == nil {
		return false
	}

	switch av := a.(type) {
	case map[string]interface{}:
		if bv, ok := b.(map[string]interface{}); ok {
			if len(av) != len(bv) {
				return false
			}
			for k, v := range av {
				if !deepEqual(v, bv[k]) {
					return false
				}
			}
			return true
		}
		return false
	case []interface{}:
		if bv, ok := b.([]interface{}); ok {
			if len(av) != len(bv) {
				return false
			}
			for i, v := range av {
				if !deepEqual(v, bv[i]) {
					return false
				}
			}
			return true
		}
		return false
	default:
		return a == b
	}
}

// ToLuaTable converts a Go interface{} (map or array) to a Lua table
// This should only be called with map[string]interface{} or []interface{} from JSON unmarshaling
func ToLuaTable(L *lua.LState, data interface{}) (*lua.LTable, error) {
	switch v := data.(type) {
	case map[string]interface{}:
		table := L.CreateTable(0, len(v))
		for key, value := range v {
			table.RawSetString(key, ToLuaValue(L, value))
		}
		return table, nil

	case []interface{}:
		table := L.CreateTable(len(v), 0)
		for i, value := range v {
			table.RawSetInt(i+1, ToLuaValue(L, value)) // Lua arrays are 1-indexed
		}
		return table, nil

	default:
		// This should only happen with invalid JSON (root-level primitives)
		return nil, fmt.Errorf("expected table or array, got %T", v)
	}
}

// ToLuaValue converts a Go interface{} to a Lua value
func ToLuaValue(L *lua.LState, data interface{}) lua.LValue {
	switch v := data.(type) {
	case map[string]interface{}:
		table := L.CreateTable(0, len(v))
		for key, value := range v {
			table.RawSetString(key, ToLuaValue(L, value))
		}
		return table

	case []interface{}:
		table := L.CreateTable(len(v), 0)
		for i, value := range v {
			table.RawSetInt(i+1, ToLuaValue(L, value)) // Lua arrays are 1-indexed
		}
		return table

	case string:
		return lua.LString(v)

	case float64:
		return lua.LNumber(v)

	case bool:
		return lua.LBool(v)

	case nil:
		return lua.LNil

	default:
		// This should never happen with JSON-unmarshaled data
		return lua.LNil
	}
}