package tools

import (
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"log/slog"
	"os/exec"
	"path/filepath"
	"sort"
	"strings"

	"github.com/charmbracelet/crush/internal/fsext"
)

const (
	GlobToolName    = "glob"
	globDescription = `Fast file pattern matching tool that finds files by name and pattern, returning matching paths sorted by modification time (newest first).

WHEN TO USE THIS TOOL:
- Use when you need to find files by name patterns or extensions
- Great for finding specific file types across a directory structure
- Useful for discovering files that match certain naming conventions

HOW TO USE:
- Provide a glob pattern to match against file paths
- Optionally specify a starting directory (defaults to current working directory)
- Results are sorted with most recently modified files first

GLOB PATTERN SYNTAX:
- '*' matches any sequence of non-separator characters
- '**' matches any sequence of characters, including separators
- '?' matches any single non-separator character
- '[...]' matches any character in the brackets
- '[!...]' matches any character not in the brackets

COMMON PATTERN EXAMPLES:
- '*.js' - Find all JavaScript files in the current directory
- '**/*.js' - Find all JavaScript files in any subdirectory
- 'src/**/*.{ts,tsx}' - Find all TypeScript files in the src directory
- '*.{html,css,js}' - Find all HTML, CSS, and JS files

LIMITATIONS:
- Results are limited to 100 files (newest first)
- Does not search file contents (use Grep tool for that)
- Hidden files (starting with '.') are skipped

WINDOWS NOTES:
- Path separators are handled automatically (both / and \ work)
- Uses ripgrep (rg) command if available, otherwise falls back to built-in Go implementation

TIPS:
- Patterns should use forward slashes (/) for cross-platform compatibility
- For the most useful results, combine with the Grep tool: first find files with Glob, then search their contents with Grep
- When doing iterative exploration that may require multiple rounds of searching, consider using the Agent tool instead
- Always check if results are truncated and refine your search pattern if needed`
)

type GlobParams struct {
	Pattern string `json:"pattern"`
	Path    string `json:"path"`
}

type GlobResponseMetadata struct {
	NumberOfFiles int  `json:"number_of_files"`
	Truncated     bool `json:"truncated"`
}

type globTool struct {
	workingDir string
}

func NewGlobTool(workingDir string) BaseTool {
	return &globTool{
		workingDir: workingDir,
	}
}

func (g *globTool) Name() string {
	return GlobToolName
}

func (g *globTool) Info() ToolInfo {
	return ToolInfo{
		Name:        GlobToolName,
		Description: globDescription,
		Parameters: map[string]any{
			"pattern": map[string]any{
				"type":        "string",
				"description": "The glob pattern to match files against",
			},
			"path": map[string]any{
				"type":        "string",
				"description": "The directory to search in. Defaults to the current working directory.",
			},
		},
		Required: []string{"pattern"},
	}
}

func (g *globTool) Run(ctx context.Context, call ToolCall) (ToolResponse, error) {
	var params GlobParams
	if err := json.Unmarshal([]byte(call.Input), &params); err != nil {
		return NewTextErrorResponse(fmt.Sprintf("error parsing parameters: %s", err)), nil
	}

	if params.Pattern == "" {
		return NewTextErrorResponse("pattern is required"), nil
	}

	searchPath := params.Path
	if searchPath == "" {
		searchPath = g.workingDir
	}

	files, truncated, err := globFiles(params.Pattern, searchPath, 100)
	if err != nil {
		return ToolResponse{}, fmt.Errorf("error finding files: %w", err)
	}

	var output string
	if len(files) == 0 {
		output = "No files found"
	} else {
		output = strings.Join(files, "\n")
		if truncated {
			output += "\n\n(Results are truncated. Consider using a more specific path or pattern.)"
		}
	}

	return WithResponseMetadata(
		NewTextResponse(output),
		GlobResponseMetadata{
			NumberOfFiles: len(files),
			Truncated:     truncated,
		},
	), nil
}

func globFiles(pattern, searchPath string, limit int) ([]string, bool, error) {
	cmdRg := fsext.GetRgCmd(pattern)
	if cmdRg != nil {
		cmdRg.Dir = searchPath
		matches, err := runRipgrep(cmdRg, searchPath, limit)
		if err == nil {
			return matches, len(matches) >= limit && limit > 0, nil
		}
		slog.Warn(fmt.Sprintf("Ripgrep execution failed: %v. Falling back to doublestar.", err))
	}

	return fsext.GlobWithDoubleStar(pattern, searchPath, limit)
}

func runRipgrep(cmd *exec.Cmd, searchRoot string, limit int) ([]string, error) {
	out, err := cmd.CombinedOutput()
	if err != nil {
		if ee, ok := err.(*exec.ExitError); ok && ee.ExitCode() == 1 {
			return nil, nil
		}
		return nil, fmt.Errorf("ripgrep: %w\n%s", err, out)
	}

	var matches []string
	for p := range bytes.SplitSeq(out, []byte{0}) {
		if len(p) == 0 {
			continue
		}
		absPath := string(p)
		if !filepath.IsAbs(absPath) {
			absPath = filepath.Join(searchRoot, absPath)
		}
		if fsext.SkipHidden(absPath) {
			continue
		}
		matches = append(matches, absPath)
	}

	sort.SliceStable(matches, func(i, j int) bool {
		return len(matches[i]) < len(matches[j])
	})

	if limit > 0 && len(matches) > limit {
		matches = matches[:limit]
	}
	return matches, nil
}