package assets

import (
	"flag"
	"fmt"
	"io"
	"os"
	"path/filepath"
	"strings"

	"git.westgate.pw/ShadowsOverWestgate/sow-tools/internal/assets/mdl"
)

// runFixMDL lowercases .mdl filenames and rewrites ASCII model identity to
// match each file's stem. Binary models are skipped (the engine owns those).
func runFixMDL(args []string, stdout, stderr io.Writer) int {
	fs := flag.NewFlagSet("fix-mdl", flag.ContinueOnError)
	fs.SetOutput(stderr)
	dryRun := fs.Bool("dry-run", false, "report changes without touching disk")
	nonRecursive := fs.Bool("non-recursive", false, "do not descend into subdirectories")
	if err := fs.Parse(args); err != nil {
		return exitUsage
	}
	paths := fs.Args()
	if len(paths) == 0 {
		fmt.Fprintln(stderr, "assets fix-mdl: usage: fix-mdl [--dry-run] <path>...")
		return exitUsage
	}

	files, err := walk(paths, mdlExt, !*nonRecursive)
	if err != nil {
		fmt.Fprintln(stderr, "assets fix-mdl:", err)
		return exitUsage
	}

	changed := 0
	failed := false
	for _, f := range files {
		// 1. Lowercase the basename if needed.
		//
		// ponytail: 35k files are each read once here (CheckNames + the rewrite
		// on candidates). The shell reference batched an awk pass to avoid
		// per-file subprocess spawns; in Go a plain read is cheap, so the batch
		// is not worth porting. If profiling ever shows this hot, parallelize
		// the loop.
		lower := f
		if base := filepath.Base(f); base != strings.ToLower(base) {
			lower = filepath.Join(filepath.Dir(f), strings.ToLower(base))
			if _, err := os.Stat(lower); err == nil {
				fmt.Fprintf(stderr, "assets fix-mdl: lowercase collision: %s -> %s\n", f, lower)
				failed = true
				continue
			}
			if *dryRun {
				fmt.Fprintf(stdout, "would lowercase: %s -> %s\n", f, lower)
			} else {
				if err := os.Rename(f, lower); err != nil {
					fmt.Fprintf(stderr, "assets fix-mdl: failed to lowercase %s: %v\n", f, err)
					failed = true
					continue
				}
				fmt.Fprintf(stdout, "lowercased: %s -> %s\n", f, lower)
			}
			changed++
		}

		// 2. Rewrite model identity if the (lowercased) file has a mismatch.
		//    In dry-run the on-disk file is still the original path.
		readPath := lower
		if *dryRun && lower != f {
			readPath = f
		}
		data, err := os.ReadFile(readPath)
		if err != nil {
			fmt.Fprintln(stderr, "assets fix-mdl:", err)
			failed = true
			continue
		}
		out, wasChanged := mdl.FixNames(data, mdl.ExpectedName(lower))
		if !wasChanged {
			continue
		}
		if *dryRun {
			fmt.Fprintf(stdout, "would fix: %s\n", lower)
		} else {
			if err := os.WriteFile(lower, out, 0o644); err != nil {
				fmt.Fprintln(stderr, "assets fix-mdl:", err)
				failed = true
				continue
			}
			fmt.Fprintf(stdout, "fixed: %s\n", lower)
		}
		changed++
	}

	if changed == 0 {
		fmt.Fprintln(stdout, "no broken mdl model names found")
	}
	if failed {
		return exitFail
	}
	return exitOK
}