package main

import (
	"bytes"
	"fmt"
	"io"
	"os"
	"os/exec"
	"path/filepath"
	"sort"
	"strings"

	"git.dev.alexdunmow.com/block/check-safety/internal/helpers"
)

const defaultPrettierConfig = `module.exports = {
	arrowParens: "always",
	bracketSameLine: true,
	bracketSpacing: true,
	experimentalTernaries: true,
	printWidth: 200,
	quoteProps: "consistent",
	semi: true,
	singleQuote: false,
	tabWidth: 4,
	trailingComma: "all",
	useTabs: true,
};
`

func runStrictGoLint(repoRoot string, backendDirs []string, pluginRoots []string) (completed []string, skipped []string, failures []goLintFailure, err error) {
	targets, skipped, err := discoverGoLintTargets(repoRoot, backendDirs, pluginRoots)
	if err != nil {
		return nil, nil, nil, err
	}

	goBin, err := exec.LookPath("go")
	if err != nil {
		return nil, nil, nil, fmt.Errorf("go not found in PATH")
	}

	golangciLint, err := exec.LookPath("golangci-lint")
	if err != nil {
		return nil, nil, nil, fmt.Errorf("golangci-lint not found in PATH")
	}

	return runStrictGoLintWithBinaries(targets, skipped, goBin, golangciLint)
}

func runStrictGoLintWithBinaries(targets []goLintTarget, skippedTargets []string, goBin string, golangciLint string) (completed []string, skipped []string, failures []goLintFailure, err error) {
	lintArgs := []string{
		"run",
		"--default=none",
		"--enable=errcheck",
		"--enable=govet",
		"--enable=ineffassign",
		"--enable=staticcheck",
		"--enable=unused",
		"./...",
	}
	lintFixArgs := []string{
		"run",
		"--fix",
		"--default=none",
		"--enable=errcheck",
		"--enable=govet",
		"--enable=ineffassign",
		"--enable=staticcheck",
		"--enable=unused",
		"./...",
	}

	for _, target := range targets {
		output, runErr := runCommand(target.moduleRoot, goBin, "fix", "./...")
		if runErr != nil {
			failures = append(failures, goLintFailure{
				target: target.label,
				stage:  "go fix ./...",
				output: output,
			})
			continue
		}

		output, runErr = runCommand(target.moduleRoot, golangciLint, lintFixArgs...)
		if runErr != nil {
			failures = append(failures, goLintFailure{
				target: target.label,
				stage:  "golangci-lint run --fix",
				output: output,
			})
			continue
		}

		output, runErr = runCommand(target.moduleRoot, goBin, "test", "-run=^$", "./...")
		if runErr != nil {
			failures = append(failures, goLintFailure{
				target: target.label,
				stage:  "go test -run=^$ ./...",
				output: output,
			})
			continue
		}

		output, runErr = runCommand(target.moduleRoot, goBin, "vet", "./...")
		if runErr != nil {
			failures = append(failures, goLintFailure{
				target: target.label,
				stage:  "go vet ./...",
				output: output,
			})
			continue
		}

		output, runErr = runCommand(target.moduleRoot, golangciLint, lintArgs...)
		if runErr != nil {
			failures = append(failures, goLintFailure{
				target: target.label,
				stage:  "golangci-lint run",
				output: output,
			})
			continue
		}
		completed = append(completed, target.label)
	}

	sort.Strings(completed)
	sort.Strings(skippedTargets)
	return completed, skippedTargets, failures, nil
}

func runFrontendAutoFixAndLint(repoRoot string, scanTargets []frontendScanTarget) (completed []string, skipped []string, failures []frontendLintFailure, err error) {
	targets, skipped, err := discoverFrontendLintTargets(repoRoot, scanTargets)
	if err != nil {
		return nil, nil, nil, err
	}
	toolRepoRoot := blockNinjaRepoRoot()

	for _, target := range targets {
		if target.hasTypeScript {
			if target.tsconfigPath == "" {
				failures = append(failures, frontendLintFailure{
					target: target.label,
					stage:  "tsc --noEmit",
					output: "TypeScript sources found but no tsconfig.json was located for this frontend target",
				})
				continue
			}

			tscBin, err := resolveRequiredBinaryWithPath("tsc",
				filepath.Join(target.packageRoot, "node_modules", ".bin", "tsc"),
				filepath.Join(repoRoot, "web", "node_modules", ".bin", "tsc"),
				filepath.Join(repoRoot, "node_modules", ".bin", "tsc"),
				filepath.Join(toolRepoRoot, "web", "node_modules", ".bin", "tsc"),
				filepath.Join(toolRepoRoot, "node_modules", ".bin", "tsc"),
			)
			if err != nil {
				return nil, nil, nil, err
			}

			output, runErr := runFrontendTypecheck(repoRoot, toolRepoRoot, target, tscBin)
			if runErr != nil {
				failures = append(failures, frontendLintFailure{
					target: target.label,
					stage:  "tsc --noEmit",
					output: output,
				})
				continue
			}
		}

		prettierBin, err := resolveRequiredBinaryWithPath("prettier",
			filepath.Join(target.packageRoot, "node_modules", ".bin", "prettier"),
			filepath.Join(repoRoot, "node_modules", ".bin", "prettier"),
			filepath.Join(toolRepoRoot, "node_modules", ".bin", "prettier"),
		)
		if err != nil {
			return nil, nil, nil, err
		}
		eslintBin, err := resolveRequiredBinaryWithPath("eslint", eslintBinaryCandidates(repoRoot, toolRepoRoot, target)...)
		if err != nil {
			return nil, nil, nil, err
		}

		if output, runErr := runCommand(target.packageRoot, prettierBin, "--write", target.sourceArg); runErr != nil {
			failures = append(failures, frontendLintFailure{
				target: target.label,
				stage:  "prettier --write",
				output: output,
			})
			continue
		}

		if output, runErr := runCommand(target.packageRoot, eslintBin, eslintArgs(target, true)...); runErr != nil {
			failures = append(failures, frontendLintFailure{
				target: target.label,
				stage:  "eslint --fix",
				output: output,
			})
			continue
		}

		if output, runErr := runCommand(target.packageRoot, eslintBin, eslintArgs(target, false)...); runErr != nil {
			failures = append(failures, frontendLintFailure{
				target: target.label,
				stage:  "eslint",
				output: output,
			})
			continue
		}

		completed = append(completed, target.label)
	}

	sort.Strings(completed)
	sort.Strings(skipped)
	return completed, skipped, failures, nil
}

func eslintArgs(target frontendLintTarget, fix bool) []string {
	args := []string{
		target.sourceArg,
		"--no-error-on-unmatched-pattern",
	}
	if !usesFlatESLintConfig(target.configPath) {
		args = append(args, "--ext", ".js,.jsx,.ts,.tsx")
	}
	if fix {
		args = append(args, "--fix")
	} else {
		args = append(args, "--max-warnings", "0")
	}
	return args
}

func eslintBinaryCandidates(repoRoot, toolRepoRoot string, target frontendLintTarget) []string {
	workspaceCandidates := []string{
		filepath.Join(repoRoot, "web", "node_modules", ".bin", "eslint"),
		filepath.Join(repoRoot, "node_modules", ".bin", "eslint"),
		filepath.Join(toolRepoRoot, "web", "node_modules", ".bin", "eslint"),
		filepath.Join(toolRepoRoot, "node_modules", ".bin", "eslint"),
	}
	localCandidate := filepath.Join(target.packageRoot, "node_modules", ".bin", "eslint")
	if target.managedConfigs {
		return append(workspaceCandidates, localCandidate)
	}
	return append([]string{localCandidate}, workspaceCandidates...)
}

func runFrontendTypecheck(repoRoot, toolRepoRoot string, target frontendLintTarget, tscBin string) (string, error) {
	if target.pluginRules {
		return runPluginFrontendTypecheck(repoRoot, toolRepoRoot, target, tscBin)
	}

	tsconfigArg, err := filepath.Rel(target.packageRoot, target.tsconfigPath)
	if err != nil {
		return "", err
	}

	return runCommand(
		target.packageRoot,
		tscBin,
		"--noEmit",
		"--pretty", "false",
		"-p", tsconfigArg,
	)
}

func runPluginFrontendTypecheck(repoRoot, toolRepoRoot string, target frontendLintTarget, tscBin string) (string, error) {
	hostNodeModules, err := resolvePluginWorkspaceNodeModules(repoRoot, toolRepoRoot)
	if err != nil {
		return "", err
	}

	tempRoot, err := os.MkdirTemp("", "check-safety-plugin-tsc-*")
	if err != nil {
		return "", err
	}
	defer helpers.LogDeferredError(nil, "remove temporary plugin typecheck root", func() error {
		return os.RemoveAll(tempRoot)
	}, "path", tempRoot)

	tempPackageRoot := filepath.Join(tempRoot, "package")
	if err := copyFrontendPackageForTypecheck(target.packageRoot, tempPackageRoot); err != nil {
		return "", err
	}

	tempNodeModules := filepath.Join(tempPackageRoot, "node_modules")
	if err := os.MkdirAll(tempNodeModules, 0755); err != nil {
		return "", err
	}
	localNodeModules := filepath.Join(target.packageRoot, "node_modules")
	if dirExists(localNodeModules) {
		if err := mergeNodeModules(localNodeModules, tempNodeModules); err != nil {
			return "", err
		}
	}
	if err := mergeNodeModules(hostNodeModules, tempNodeModules); err != nil {
		return "", err
	}

	relTSConfig, err := filepath.Rel(target.packageRoot, target.tsconfigPath)
	if err != nil {
		return "", err
	}

	return runCommand(
		tempPackageRoot,
		tscBin,
		"--noEmit",
		"--pretty", "false",
		"-p", relTSConfig,
	)
}

func resolveRequiredBinaryWithPath(binaryName string, candidates ...string) (string, error) {
	for _, candidate := range candidates {
		info, err := os.Stat(candidate)
		if err == nil && !info.IsDir() {
			return candidate, nil
		}
	}
	if binaryName != "" {
		if path, err := exec.LookPath(binaryName); err == nil {
			return path, nil
		}
	}
	return "", fmt.Errorf("required frontend tool not found: %s", strings.Join(candidates, ", "))
}

func resolvePluginWorkspaceNodeModules(repoRoot, toolRepoRoot string) (string, error) {
	for _, candidate := range []string{
		filepath.Join(repoRoot, "web", "node_modules"),
		filepath.Join(toolRepoRoot, "web", "node_modules"),
	} {
		info, err := os.Stat(candidate)
		if err == nil && info.IsDir() {
			return candidate, nil
		}
	}

	return "", fmt.Errorf("plugin frontend typecheck requires a BlockNinja workspace node_modules directory")
}

func mergeNodeModules(srcRoot, dstRoot string) error {
	entries, err := os.ReadDir(srcRoot)
	if err != nil {
		return err
	}

	for _, entry := range entries {
		srcPath := filepath.Join(srcRoot, entry.Name())
		dstPath := filepath.Join(dstRoot, entry.Name())

		if entry.Name() == ".bin" || strings.HasPrefix(entry.Name(), "@") {
			if err := os.MkdirAll(dstPath, 0755); err != nil {
				return err
			}
			if err := mergeNodeModules(srcPath, dstPath); err != nil {
				return err
			}
			continue
		}

		if _, err := os.Lstat(dstPath); err == nil {
			continue
		} else if !os.IsNotExist(err) {
			return err
		}

		if err := os.Symlink(srcPath, dstPath); err != nil {
			return err
		}
	}

	return nil
}

func copyFrontendPackageForTypecheck(srcRoot, dstRoot string) error {
	return filepath.Walk(srcRoot, func(path string, info os.FileInfo, err error) error {
		if err != nil {
			return err
		}

		relPath, err := filepath.Rel(srcRoot, path)
		if err != nil {
			return err
		}
		if relPath == "." {
			return os.MkdirAll(dstRoot, 0755)
		}

		if info.IsDir() {
			switch info.Name() {
			case "node_modules", "dist", "build", ".git":
				return filepath.SkipDir
			}
			return os.MkdirAll(filepath.Join(dstRoot, relPath), info.Mode())
		}

		dstPath := filepath.Join(dstRoot, relPath)
		return copyFile(path, dstPath, info.Mode())
	})
}

func copyFile(srcPath, dstPath string, mode os.FileMode) error {
	src, err := os.Open(srcPath)
	if err != nil {
		return err
	}
	defer helpers.LogDeferredError(nil, "close lint temp source file", src.Close, "path", srcPath)

	if err := os.MkdirAll(filepath.Dir(dstPath), 0755); err != nil {
		return err
	}

	dst, err := os.OpenFile(dstPath, os.O_CREATE|os.O_TRUNC|os.O_WRONLY, mode)
	if err != nil {
		return err
	}
	defer helpers.LogDeferredError(nil, "close lint temp destination file", dst.Close, "path", dstPath)

	if _, err := io.Copy(dst, src); err != nil {
		return err
	}

	return nil
}

func blockNinjaRepoRoot() string {
	home, err := os.UserHomeDir()
	if err != nil {
		return ""
	}
	return filepath.Join(home, "src", "blockninja", "cms")
}

func orchestratorRepoRoot() string {
	home, err := os.UserHomeDir()
	if err != nil {
		return ""
	}
	return filepath.Join(home, "src", "blockninja", "orchestrator")
}

func ensureDefaultFrontendConfigs(repoRoot, packageRoot string) error {
	if err := ensureDefaultESLintConfig(repoRoot, packageRoot); err != nil {
		return err
	}
	if err := ensureDefaultPrettierConfig(repoRoot, packageRoot); err != nil {
		return err
	}
	return nil
}

func ensureDefaultESLintConfig(repoRoot, packageRoot string) error {
	if _, ok := findNearestESLintConfig(packageRoot); ok {
		return nil
	}

	configPath := filepath.Join(packageRoot, "eslint.config.js")
	sourceConfig := filepath.Join(repoRoot, "web", "eslint.config.js")
	if !fileExists(sourceConfig) {
		sourceConfig = filepath.Join(blockNinjaRepoRoot(), "web", "eslint.config.js")
	}
	relImport, err := filepath.Rel(packageRoot, sourceConfig)
	if err != nil {
		return err
	}
	relImport = filepath.ToSlash(relImport)
	if !strings.HasPrefix(relImport, ".") {
		relImport = "./" + relImport
	}

	content := fmt.Sprintf("import config from %q\n\nexport default config\n", relImport)
	return os.WriteFile(configPath, []byte(content), 0644)
}

func ensureDefaultPrettierConfig(repoRoot, packageRoot string) error {
	for _, name := range []string{
		"prettier.config.js",
		"prettier.config.mjs",
		"prettier.config.cjs",
		".prettierrc",
		".prettierrc.js",
		".prettierrc.cjs",
		".prettierrc.json",
		".prettierrc.yaml",
		".prettierrc.yml",
	} {
		if info, err := os.Stat(filepath.Join(packageRoot, name)); err == nil && !info.IsDir() {
			return nil
		}
	}

	configPath := filepath.Join(packageRoot, "prettier.config.cjs")
	return os.WriteFile(configPath, []byte(defaultPrettierConfig), 0644)
}

func runCommand(workdir string, name string, args ...string) (string, error) {
	cmd := exec.Command(name, args...)
	cmd.Dir = workdir

	var stdout bytes.Buffer
	var stderr bytes.Buffer
	cmd.Stdout = &stdout
	cmd.Stderr = &stderr

	err := cmd.Run()
	output := strings.TrimSpace(stdout.String())
	errOutput := strings.TrimSpace(stderr.String())

	switch {
	case output == "" && errOutput == "":
		return "", err
	case output == "":
		return errOutput, err
	case errOutput == "":
		return output, err
	default:
		return output + "\n" + errOutput, err
	}
}