BigChef/processor/regex.go

package processor

import (
	"fmt"
	"log"
	"regexp"
	"strconv"
	"strings"

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

// RegexProcessor implements the Processor interface using regex patterns
type RegexProcessor struct{}

// ToLua sets capture groups as Lua variables (v1, v2, etc. for numeric values and s1, s2, etc. for strings)
func (p *RegexProcessor) ToLua(L *lua.LState, data interface{}) error {
	captures, ok := data.([]string)
	if !ok {
		return fmt.Errorf("expected []string for captures, got %T", data)
	}

	// Set variables for each capture group, starting from v1/s1 for the first capture
	for i := 0; i < len(captures); i++ {
		// Set string version (always available as s1, s2, etc.)
		L.SetGlobal(fmt.Sprintf("s%d", i+1), lua.LString(captures[i]))

		// Try to convert to number and set v1, v2, etc.
		if val, err := strconv.ParseFloat(captures[i], 64); err == nil {
			L.SetGlobal(fmt.Sprintf("v%d", i+1), lua.LNumber(val))
		}
	}

	return nil
}

// FromLua implements the Processor interface for RegexProcessor
func (p *RegexProcessor) FromLua(L *lua.LState) (interface{}, error) {
	// Get the modified values after Lua execution
	modifications := make(map[int]string)

	// Check for modifications to v1-v12 and s1-s12
	for i := 0; i < 12; i++ {
		// Check both v and s variables to see if any were modified
		vVarName := fmt.Sprintf("v%d", i+1)
		sVarName := fmt.Sprintf("s%d", i+1)

		vLuaVal := L.GetGlobal(vVarName)
		sLuaVal := L.GetGlobal(sVarName)

		// If our value is a number then it's very likely we want it to be a number
		// And not a string
		// If we do want it to be a string we will cast it into a string in lua
		// wait that wouldn't work... Casting v to a string would not load it here
		if vLuaVal.Type() == lua.LTNumber {
			modifications[i] = vLuaVal.String()
			continue
		}
		if sLuaVal.Type() == lua.LTString {
			modifications[i] = sLuaVal.String()
			continue
		}

	}

	return modifications, nil
}

type NamedCapture struct {
	Name  string
	Value string
	Range [2]int
}

// ProcessContent applies regex replacement with Lua processing
func (p *RegexProcessor) ProcessContent(content string, pattern string, luaExpr string) (string, int, int, error) {
	// Handle special pattern modifications
	if !strings.HasPrefix(pattern, "(?s)") {
		pattern = "(?s)" + pattern
		log.Printf("Pattern modified to include (?s): %s", pattern)
	}

	pattern = strings.ReplaceAll(pattern, "!num", `"?(\d*\.?\d+)"?`)
	pattern = strings.ReplaceAll(pattern, "!any", `.*?`)
	repPattern := regexp.MustCompile(`!rep\(([^,]+),\s*(\d+)\)`)
	// !rep(pattern, count) repeats the pattern n times
	// Inserting !any between each repetition
	pattern = repPattern.ReplaceAllStringFunc(pattern, func(match string) string {
		parts := repPattern.FindStringSubmatch(match)
		if len(parts) != 3 {
			return match
		}
		repeatedPattern := parts[1]
		count := parts[2]
		repetitions, _ := strconv.Atoi(count)
		return strings.Repeat(repeatedPattern+".*?", repetitions-1) + repeatedPattern
	})

	compiledPattern, err := regexp.Compile(pattern)
	if err != nil {
		log.Printf("Error compiling pattern: %v", err)
		return "", 0, 0, fmt.Errorf("error compiling pattern: %v", err)
	}
	log.Printf("Compiled pattern successfully: %s", pattern)

	previous := luaExpr
	luaExpr = BuildLuaScript(luaExpr)
	log.Printf("Changing Lua expression from: %s to: %s", previous, luaExpr)

	L, err := NewLuaState()
	if err != nil {
		log.Printf("Error creating Lua state: %v", err)
		return "", 0, 0, fmt.Errorf("error creating Lua state: %v", err)
	}
	defer L.Close()
	log.Printf("Lua state created successfully")

	// Initialize Lua environment
	modificationCount := 0

	// Process all regex matches
	result := content
	indices := compiledPattern.FindAllStringSubmatchIndex(content, -1)
	log.Printf("Found %d matches in the content", len(indices))

	// We walk backwards because we're replacing something with something else that might be longer
	// And in the case it is longer than the original all indicces past that change will be fucked up
	// By going backwards we fuck up all the indices to the end of the file that we don't care about
	// Because there either aren't any (last match) or they're already modified (subsequent matches)
	for i := len(indices) - 1; i >= 0; i-- {
		matchIndices := indices[i]
		log.Printf("Processing match indices: %v", matchIndices)

		// Why we're doing this whole song and dance of indices is to properly handle empty matches
		// Plus it's a little cleaner to surgically replace our matches
		// If we were to use string.replace and encountered an empty match there'd be nothing to replace
		// But using indices an empty match would have its starting and ending indices be the same
		// So when we're cutting open the array we say 0:7 + modified + 7:end
		// As if concatenating in the middle of the array
		// Plus it supports lookarounds
		match := content[matchIndices[0]:matchIndices[1]]
		log.Printf("Matched content: %s", match)

		groups := matchIndices[2:]
		if len(groups) <= 0 {
			log.Println("No capture groups for lua to chew on")
			continue
		}
		if len(groups)%2 == 1 {
			log.Println("Odd number of indices of groups, what the fuck?")
			continue
		}

		captures := make([]string, 0, len(groups)/2)
		for j := 0; j < len(groups); j += 2 {
			captures = append(captures, content[groups[j]:groups[j+1]])
		}
		log.Printf("Captured groups: %v", captures)

		// We have to use array to preserve order
		// Very important for the reconstruction step
		// Because we must overwrite the values in reverse order
		// See comments a few dozen lines above for more details
		namedCaptures := make([]NamedCapture, 0, len(groups)/2)
		groupNames := compiledPattern.SubexpNames()[1:]
		for i, name := range groupNames {
			if name == "" {
				continue
			}
			namedCaptures = append(namedCaptures, NamedCapture{
				Name:  name,
				Value: captures[i],
				Range: [2]int{groups[i*2], groups[i*2+1]},
			})
		}

		log.Printf("Named captures: %v", namedCaptures)

		if err := p.ToLua(L, captures); err != nil {
			log.Printf("Error setting Lua variables: %v", err)
			continue
		}
		log.Println("Lua variables set successfully")

		for _, capture := range namedCaptures {
			if capture.Name == "" {
				continue
			}
			if val, err := strconv.ParseFloat(capture.Value, 64); err == nil {
				L.SetGlobal(capture.Name, lua.LNumber(val))
			} else {
				L.SetGlobal(capture.Name, lua.LString(capture.Value))
			}
		}

		if err := L.DoString(luaExpr); err != nil {
			log.Printf("Error executing Lua code %s for group %s: %v", luaExpr, captures, err)
			continue
		}
		log.Println("Lua code executed successfully")

		// Get modifications from Lua
		modResult, err := p.FromLua(L)
		if err != nil {
			log.Printf("Error getting modifications: %v", err)
			continue
		}

		// Apply modifications to the matched text
		modsMap, ok := modResult.(map[int]string)
		if !ok || len(modsMap) == 0 {
			log.Println("No modifications to apply")
			continue
		}

		replacement := ""
		replacementVar := L.GetGlobal("replacement")
		if replacementVar.Type() != lua.LTNil {
			replacement = replacementVar.String()
		}
		if replacement == "" {
			// Apply the modifications to the original match
			replacement = match
			for i := len(modsMap) - 1; i >= 0; i-- {
				newVal := modsMap[i]
				log.Printf("Applying modification: %s", newVal)
				// Indices of the group are relative to content
				// To relate them to match we have to subtract the match start index
				groupStart := groups[i*2] - matchIndices[0]
				groupEnd := groups[i*2+1] - matchIndices[0]
				replacement = replacement[:groupStart] + newVal + replacement[groupEnd:]
			}

			for i := len(namedCaptures) - 1; i >= 0; i-- {
				capture := namedCaptures[i]
				if capture.Name == "" {
					continue
				}
				groupStart := capture.Range[0] - matchIndices[0]
				groupEnd := capture.Range[1] - matchIndices[0]
				luaValue := L.GetGlobal(capture.Name).String()
				replacement = replacement[:groupStart] + luaValue + replacement[groupEnd:]
			}
		}
		modificationCount++
		result = result[:matchIndices[0]] + replacement + result[matchIndices[1]:]
		log.Printf("Modification count updated: %d", modificationCount)
	}

	log.Printf("Process completed with %d modifications", modificationCount)
	return result, modificationCount, len(indices), nil
}