package sidekick

import (
  "fmt"
  "os"
  "os/exec"
  "regexp"
  "strings"
)

// DefaultInternalTools returns a map of standard file I/O tools
func DefaultInternalTools() map[string]ToolDefinition {
  return map[string]ToolDefinition{
    "read_file": {
      Name:        "read_file",
      Description: "Read a file, optionally with line windowing. Every line is prefixed with 'line:hash:' (e.g. '1:abcd:content').",
      Parameters: map[string]interface{}{
        "type": "object",
        "properties": map[string]interface{}{
          "path":   map[string]interface{}{"type": "string"},
          "offset": map[string]interface{}{"type": "integer", "description": "Starting line number (0-indexed)"},
          "limit":  map[string]interface{}{"type": "integer", "description": "Number of lines to read"},
        },
        "required": []string{"path"},
      },
      Internal: true,
      Handler:  readFileHandler,
    },
    "write_file": {
      Name:        "write_file",
      Description: "Overwrite a file with new content. Automatically strips 'line:hash:' prefixes if present.",
      Parameters: map[string]interface{}{
        "type": "object",
        "properties": map[string]interface{}{
          "path":    map[string]interface{}{"type": "string"},
          "content": map[string]interface{}{"type": "string"},
        },
        "required": []string{"path", "content"},
      },
      Internal: true,
      Handler:  writeFileHandler,
    },
    "grep_file": {
      Name:        "grep_file",
      Description: "Regex search with surrounding context. Every line is prefixed with 'line:hash:' (e.g. '1:abcd:content').",
      Parameters: map[string]interface{}{
        "type": "object",
        "properties": map[string]interface{}{
          "path":          map[string]interface{}{"type": "string"},
          "pattern":       map[string]interface{}{"type": "string"},
          "context_lines": map[string]interface{}{"type": "integer"},
        },
        "required": []string{"path", "pattern"},
      },
      Internal: true,
      Handler:  grepFileHandler,
    },
    "edit_file": {
      Name:        "edit_file",
      Description: "Replace a string or a block of lines in a file. If 'old_string' contains 'line:hash:' prefixes for every line, it performs a precise replacement at the specified line numbers. Otherwise, it performs a standard first-occurrence replacement. Both multiline strings and 'line:hash:' stripping are supported.",
      Parameters: map[string]interface{}{
        "type": "object",
        "properties": map[string]interface{}{
          "path":       map[string]interface{}{"type": "string"},
          "old_string": map[string]interface{}{"type": "string"},
          "new_string": map[string]interface{}{"type": "string"},
        },
        "required": []string{"path", "old_string", "new_string"},
      },
      Internal: true,
      Handler:  editFileHandler,
    },
    "shell_exec": {
      Name:        "shell_exec",
      Description: "Run a POSIX shell command and return its combined stdout and stderr.",
      Parameters: map[string]interface{}{
        "type": "object",
        "properties": map[string]interface{}{
          "command": map[string]interface{}{"type": "string"},
        },
        "required": []string{"command"},
      },
      Internal: true,
      Handler:  shellExecHandler,
    },
  }
}

func shellExecHandler(args map[string]interface{}) (string, error) {
  cmdStr, ok := args["command"].(string)
  if !ok {
    return "", fmt.Errorf("command is required")
  }

  cmd := exec.Command("sh", "-c", cmdStr)
  output, err := cmd.CombinedOutput()

  result := string(output)
  if err != nil {
    result = fmt.Sprintf("%s\nError: %v", result, err)
  }

  if result == "" {
    return "(empty output)", nil
  }

  return result, nil
}

func readFileHandler(args map[string]interface{}) (string, error) {
  path, ok := args["path"].(string)
  if !ok {
    return "", fmt.Errorf("path is required")
  }

  content, err := os.ReadFile(path)
  if err != nil {
    return "", err
  }

  lines := strings.Split(string(content), "\n")

  offset := 0
  if off, ok := args["offset"].(float64); ok {
    offset = int(off)
  }
  if offset < 0 {
    offset = 0
  }

  limit := len(lines)
  if lim, ok := args["limit"].(float64); ok {
    limit = int(lim)
  }

  end := offset + limit
  if end > len(lines) {
    end = len(lines)
  }
  if offset >= len(lines) {
    return "", nil // Empty reading window
  }

  var outputLines []string
  for i, line := range lines[offset:end] {
    lineNum := offset + i + 1
    outputLines = append(outputLines, fmt.Sprintf("%d:%s:%s", lineNum, hashLine(line), line))
  }

  return strings.Join(outputLines, "\n"), nil
}

func writeFileHandler(args map[string]interface{}) (string, error) {
  path, ok := args["path"].(string)
  if !ok {
    return "", fmt.Errorf("path is required")
  }
  content, ok := args["content"].(string)
  if !ok {
    return "", fmt.Errorf("content is required")
  }

  content = stripHashlines(content)

  err := os.WriteFile(path, []byte(content), 0644)
  if err != nil {
    return "", err
  }
  return fmt.Sprintf("Successfully wrote to %s", path), nil
}

func grepFileHandler(args map[string]interface{}) (string, error) {
  path, ok := args["path"].(string)
  if !ok {
    return "", fmt.Errorf("path is required")
  }
  pattern, ok := args["pattern"].(string)
  if !ok {
    return "", fmt.Errorf("pattern is required")
  }

  contextLines := 0
  if cl, ok := args["context_lines"].(float64); ok {
    contextLines = int(cl)
  }

  content, err := os.ReadFile(path)
  if err != nil {
    return "", err
  }

  lines := strings.Split(string(content), "\n")
  re, err := regexp.Compile(pattern)
  if err != nil {
    return "", fmt.Errorf("invalid regex: %w", err)
  }

  var results []string
  for i, line := range lines {
    if re.MatchString(line) {
      start := i - contextLines
      if start < 0 {
        start = 0
      }
      end := i + contextLines + 1
      if end > len(lines) {
        end = len(lines)
      }

      results = append(results, fmt.Sprintf("--- Match around line %d ---", i+1))
      for j := start; j < end; j++ {
        results = append(results, fmt.Sprintf("%d:%s:%s", j+1, hashLine(lines[j]), lines[j]))
      }
    }
  }

  if len(results) == 0 {
    return "No matches found.", nil
  }
  return strings.Join(results, "\n"), nil
}
func editFileHandler(args map[string]interface{}) (string, error) {
  path, ok := args["path"].(string)
  if !ok {
    return "", fmt.Errorf("path is required")
  }
  oldStr, ok := args["old_string"].(string)
  if !ok {
    return "", fmt.Errorf("old_string is required")
  }
  newStr, ok := args["new_string"].(string)
  if !ok {
    return "", fmt.Errorf("new_string is required")
  }

  newStr = stripHashlines(newStr)

  content, err := os.ReadFile(path)
  if err != nil {
    return "", err
  }

  strContent := string(content)

  hasHashlines, startLine, strippedOldStr := parseHashlines(oldStr)

  if hasHashlines && startLine > 0 {
    fileLines := strings.Split(strContent, "\n")
    oldLines := strings.Split(strippedOldStr, "\n")

    startIdx := startLine - 1
    endIdx := startIdx + len(oldLines)

    if startIdx >= 0 && endIdx <= len(fileLines) {
      match := true
      for i := 0; i < len(oldLines); i++ {
        if fileLines[startIdx+i] != oldLines[i] {
          match = false
          break
        }
      }

      if match {
        var finalLines []string
        finalLines = append(finalLines, fileLines[:startIdx]...)
        if newStr != "" {
          finalLines = append(finalLines, strings.Split(newStr, "\n")...)
        }
        finalLines = append(finalLines, fileLines[endIdx:]...)

        newContent := strings.Join(finalLines, "\n")
        err = os.WriteFile(path, []byte(newContent), 0644)
        if err != nil {
          return "", err
        }
        return fmt.Sprintf("Successfully edited %s", path), nil
      }
    }
  }

  // Fallback to simple replacement
  strippedOldStr = stripHashlines(oldStr)
  if !strings.Contains(strContent, strippedOldStr) {
    return "", fmt.Errorf("old_string not found in file")
  }

  // Replace first occurrence only
  newContent := strings.Replace(strContent, strippedOldStr, newStr, 1)

  err = os.WriteFile(path, []byte(newContent), 0644)
  if err != nil {
    return "", err
  }

  return fmt.Sprintf("Successfully edited %s", path), nil
}

func parseHashlines(s string) (bool, int, string) {
  if s == "" {
    return false, 0, s
  }
  var result []string
  lines := strings.Split(s, "\n")
  startLine := -1
  for i, line := range lines {
    parts := strings.SplitN(line, ":", 3)
    if len(parts) == 3 {
      isDigit := len(parts[0]) > 0
      for _, c := range parts[0] {
        if c < '0' || c > '9' {
          isDigit = false
          break
        }
      }
      isHex := len(parts[1]) == 4
      for _, c := range parts[1] {
        if !((c >= '0' && c <= '9') || (c >= 'a' && c <= 'f') || (c >= 'A' && c <= 'F')) {
          isHex = false
          break
        }
      }
      if isDigit && isHex {
        if i == 0 {
          fmt.Sscanf(parts[0], "%d", &startLine)
        }
        result = append(result, parts[2])
        continue
      }
    }
    return false, 0, s
  }
  return true, startLine, strings.Join(result, "\n")
}

func stripHashlines(s string) string {
  var result []string
  lines := strings.Split(s, "\n")
  for _, line := range lines {
    parts := strings.SplitN(line, ":", 3)
    if len(parts) == 3 {
      isDigit := len(parts[0]) > 0
      for _, c := range parts[0] {
        if c < '0' || c > '9' {
          isDigit = false
          break
        }
      }
      isHex := len(parts[1]) == 4
      for _, c := range parts[1] {
        if !((c >= '0' && c <= '9') || (c >= 'a' && c <= 'f') || (c >= 'A' && c <= 'F')) {
          isHex = false
          break
        }
      }
      if isDigit && isHex {
        result = append(result, parts[2])
        continue
      }
    }
    result = append(result, line)
  }
  return strings.Join(result, "\n")
}

func hashLine(line string) string {
  var h uint32 = 2166136261
  for i := 0; i < len(line); i++ {
    h ^= uint32(line[i])
    h *= 16777619
  }
  return fmt.Sprintf("%04x", h&0xffff)
}