// SPDX-License-Identifier: GPL-3.0-or-later

package main

import (
	"fmt"
	"io"
	"os"

	"krino/internal/plan"
	"krino/internal/tui"
)

// reviewDir drives spec §8.2/§8.3's interactive review over the real
// terminal. It is a thin wrapper: reviewChains holds all the actual
// approval logic, driven here by tui.ReadKey (raw mode while stdin is a
// terminal, a plain single-byte read otherwise) via keyReader, so the exact
// same code path runs whether the input is a real keypress or, in tests, a
// strings.Reader. root is the directory being reviewed, threaded through to
// reviewChains so a per-file destination renders the same way the
// directory-level table does (root-relative inside root, ~-abbreviated
// outside it) instead of always falling back to the abbreviated form. p
// styles the prompts and the per-file steps (spec §8.2).
func reviewDir(out io.Writer, chains []plan.Chain, root string, p palette) (map[string]bool, rune, error) {
	return reviewChains(keyReader{stdin}, out, chains, root, p)
}

// keyReader adapts tui.ReadKey - one key at a time, from a real *os.File -
// to the io.Reader reviewChains expects. tui.ReadKey's own doc comment is
// why this is safe to call once per key: it always reads exactly one byte
// and restores the terminal on every path before returning.
type keyReader struct{ f *os.File }

func (k keyReader) Read(p []byte) (int, error) {
	r, err := tui.ReadKey(k.f)
	if err != nil {
		return 0, err
	}
	p[0] = byte(r)
	return 1, nil
}

// reviewChains is spec §8.2/§8.3's approval flow, and the testable core
// reviewDir wraps: the top-level
//
//	[a] apply all  [c] choose per file  [s] skip this directory  [q] quit
//
// menu, and, for [c], the per-file
//
//	[y] yes  [n] no  [a] yes to this and all remaining  [d] done, apply chosen so far  [q] quit, apply nothing
//
// prompt. action is always one of 'a', 'c', 's' or 'q': a [c] session's own
// [q] ("quit, apply nothing") folds into the same 'q' the caller already
// handles for the top-level menu, and approved is emptied to match - even a
// file already marked yes in that session is discarded, per spec §8.3's
// wording ("apply nothing"), unlike [d] ("apply chosen so far"), which
// keeps it. root is the directory being reviewed - passed only to
// reviewPerFile's destination rendering (review finding 1, fix round
// 2026-09-12); nothing here uses it directly.
func reviewChains(in io.Reader, out io.Writer, chains []plan.Chain, root string, p palette) (map[string]bool, rune, error) {
	fmt.Fprintln(out)
	for _, l := range wrapped("", "[a] apply all  [c] choose per file  [s] skip this directory  [q] quit", 0, widthPolicy(out), p.keys) {
		fmt.Fprintln(out, l)
	}
	for {
		key, err := readKey(in)
		if err != nil {
			return nil, 0, err
		}
		switch key {
		case 'a':
			return approveAll(chains), 'a', nil
		case 's':
			return map[string]bool{}, 's', nil
		case 'q':
			return map[string]bool{}, 'q', nil
		case 'c':
			approved, quit, err := reviewPerFile(in, out, chains, root, p)
			if err != nil {
				return nil, 0, err
			}
			if quit {
				return map[string]bool{}, 'q', nil
			}
			return approved, 'c', nil
		default:
			fmt.Fprintf(out, "%q is not a, c, s or q\n", key)
		}
	}
}

// reviewPerFile is spec §8.3: one prompt per file, in the order chains
// already carries them (the same order the plan above it numbered them).
// Each file shows the same block body the plan shows (stepLines): every
// step, its rule and its reason, wrapped to the terminal. [y]/[n] decide
// just that file; [a] approves it and every remaining file without asking
// again; [d] stops asking and applies whatever was already chosen,
// declining the rest; [q] aborts the review entirely, discarding even files
// already marked yes - reported back to reviewChains via quit=true. root is
// passed down so a destination inside root renders root-relative and one
// outside it renders ~-abbreviated, exactly as in the plan (review finding
// 1, fix round 2026-09-12).
func reviewPerFile(in io.Reader, out io.Writer, chains []plan.Chain, root string, p palette) (approved map[string]bool, quit bool, err error) {
	approved = map[string]bool{}
	yesRest := false
	for i, c := range chains {
		if yesRest {
			approved[c.File.Rel] = true
			continue
		}

		fmt.Fprintf(out, "\n[%d/%d] %s\n", i+1, len(chains), c.File.Rel)
		for _, l := range stepLines(c, 7, root, p, widthPolicy(out)) {
			fmt.Fprintln(out, l)
		}
		for _, l := range wrapped("  ", perFileKeys, 2, widthPolicy(out), p.keys) {
			fmt.Fprintln(out, l)
		}

		for {
			key, kerr := readKey(in)
			if kerr != nil {
				return nil, false, kerr
			}
			switch key {
			case 'y':
				approved[c.File.Rel] = true
			case 'n':
				// leave unapproved
			case 'a':
				approved[c.File.Rel] = true
				yesRest = true
			case 'd':
				return approved, false, nil
			case 'q':
				return nil, true, nil
			default:
				fmt.Fprintf(out, "%q is not y, n, a, d or q\n", key)
				continue
			}
			break
		}
	}
	return approved, false, nil
}

// perFileKeys is the per-file prompt of spec §8.3, shared by review and
// undo, and wrapped to the terminal like every other long line.
const perFileKeys = "[y] yes  [n] no  [a] yes to this and all remaining  [d] done, apply chosen so far  [q] quit, apply nothing"

// readKey reads the single byte reviewChains treats as one keypress. Over
// the real terminal that byte already came from tui.ReadKey (via
// keyReader); in a test, it is just the next byte of a strings.Reader.
func readKey(in io.Reader) (rune, error) {
	var b [1]byte
	if _, err := io.ReadFull(in, b[:]); err != nil {
		return 0, err
	}
	return rune(b[0]), nil
}

// approveAll approves every one of chains by File.Rel - [a] apply all at
// the top level, and [a] yes to this and all remaining once it fires
// mid per-file review.
func approveAll(chains []plan.Chain) map[string]bool {
	approved := make(map[string]bool, len(chains))
	for _, c := range chains {
		approved[c.File.Rel] = true
	}
	return approved
}