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

package main

import (
	"fmt"
	"io"
	"os"

	"git.labunix.xyz/krino/internal/plan"
	"git.labunix.xyz/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, map[string]plan.Kind, 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  [t] trash  [d] delete permanently  [w] write, apply chosen so far  [q] quit, apply nothing
//
// prompt. action is always one of 'a', 'c', 's', 'w' 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 [w] ("write, apply chosen so
// far"), which keeps it and is returned as 'w': the caller applies what was
// decided and stops. approved holds every file decided, true for yes and
// false for no; a file [w] left unreviewed is absent. replaced holds the
// files [t] or [d] chose to trash or delete instead of what the rules
// planned; replaceChains applies it. Enter is ignored at both prompts. root
// is the directory being reviewed - passed only to reviewPerFile's
// destination rendering; nothing here uses it directly.
func reviewChains(in io.Reader, out io.Writer, chains []plan.Chain, root string, p palette) (map[string]bool, map[string]plan.Kind, 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, nil, 0, err
		}
		switch key {
		case '\r', '\n':
			continue
		case 'a':
			return approveAll(chains), nil, 'a', nil
		case 's':
			return map[string]bool{}, nil, 's', nil
		case 'q':
			return map[string]bool{}, nil, 'q', nil
		case 'c':
			approved, replaced, end, err := reviewPerFile(in, out, chains, root, p)
			if err != nil {
				return nil, nil, 0, err
			}
			switch end {
			case 'q':
				return map[string]bool{}, nil, 'q', nil
			case 'w':
				return approved, replaced, 'w', nil
			}
			return approved, replaced, '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; [t] and [d] approve it with its chain replaced by one trash or
// permanent delete step, [d] only after a y to its own confirmation (any
// other key asks about the same file again); every choice is echoed in red
// on its own line; [w] stops asking and applies whatever was already chosen,
// leaving the rest unreviewed - reported back as end 'w'; [q] aborts the
// review entirely, discarding even files already marked yes - end 'q'. root
// is passed down so a destination inside root renders root-relative and one
// outside it renders ~-abbreviated, exactly as in the plan.
func reviewPerFile(in io.Reader, out io.Writer, chains []plan.Chain, root string, p palette) (approved map[string]bool, replaced map[string]plan.Kind, end rune, err error) {
	approved = map[string]bool{}
	replaced = map[string]plan.Kind{}
	yesRest := false
	for i, c := range chains {
		if yesRest {
			approved[c.File.Rel] = true
			continue
		}

		// The heading wraps with its continuation past the label column,
		// so a long name cannot pass for a step line.
		fmt.Fprintln(out)
		for _, l := range wrapped("", fmt.Sprintf("[%d/%d] %s", i+1, len(chains), display(c.File.Rel)), 7+labelWidth+1, widthPolicy(out), plainText) {
			fmt.Fprintln(out, l)
		}
		for _, l := range stepLines(c, 7, root, p, widthPolicy(out)) {
			fmt.Fprintln(out, l)
		}
		showKeys := true
		for {
			if showKeys {
				for _, l := range wrapped("  ", perFileKeys, 2, widthPolicy(out), p.keys) {
					fmt.Fprintln(out, l)
				}
				showKeys = false
			}
			key, kerr := readKey(in)
			if kerr != nil {
				return nil, nil, 0, kerr
			}
			var choice string
			switch key {
			case '\r', '\n':
				continue
			case 'y':
				approved[c.File.Rel] = true
				choice = "yes"
			case 'n':
				approved[c.File.Rel] = false
				choice = "no"
			case 'a':
				approved[c.File.Rel] = true
				yesRest = true
				choice = "yes, and all remaining"
			case 't':
				approved[c.File.Rel] = true
				replaced[c.File.Rel] = plan.Trash
				choice = "trash"
			case 'd':
				fmt.Fprintf(out, "  delete %s permanently? [y/N] ", display(c.File.Rel))
				confirm, kerr := readKey(in)
				if kerr != nil {
					return nil, nil, 0, kerr
				}
				fmt.Fprintln(out)
				if confirm != 'y' {
					fmt.Fprintln(out, "  not deleted")
					showKeys = true
					continue
				}
				approved[c.File.Rel] = true
				replaced[c.File.Rel] = plan.DeletePermanent
				choice = "DELETE permanently"
			case 'w':
				return approved, replaced, 'w', nil
			case 'q':
				return nil, nil, 'q', nil
			default:
				fmt.Fprintf(out, "%q is not y, n, a, t, d, w or q\n", key)
				continue
			}
			fmt.Fprintln(out, "  "+p.bad("→ "+choice))
			break
		}
	}
	return approved, replaced, 0, nil
}

// reviewedChains returns the chains of the files decided holds, yes or no,
// in order: after [w], only these go to Apply, so a file never reviewed is
// neither applied nor logged as declined.
func reviewedChains(chains []plan.Chain, decided map[string]bool) []plan.Chain {
	var out []plan.Chain
	for _, c := range chains {
		if _, ok := decided[c.File.Rel]; ok {
			out = append(out, c)
		}
	}
	return out
}

// withNotReviewed appends to an outcome line how many files [w] left
// unreviewed, when any were.
func withNotReviewed(line string, n int) string {
	if n == 0 {
		return line
	}
	return fmt.Sprintf("%s · %d not reviewed", line, n)
}

// perFileKeys is the per-file prompt of spec §8.3, wrapped to the terminal
// like every other long line. Undo's has no [t] or [d] (undoPerFileKeys).
const perFileKeys = "[y] yes  [n] no  [a] yes to this and all remaining  [t] trash  [d] delete permanently  [w] write, apply chosen so far  [q] quit, apply nothing"

// reviewRule is the rule name a step chosen in review is planned and logged
// under, in parentheses so no configured rule can be mistaken for it.
const reviewRule = "(review)"

// replaceChains returns chains with the chain of every file in replaced
// swapped for one step of the chosen kind on the file itself, under
// reviewRule: [t] and [d] set aside what the rules planned. chains itself
// is not modified.
func replaceChains(chains []plan.Chain, replaced map[string]plan.Kind) []plan.Chain {
	out := make([]plan.Chain, len(chains))
	for i, c := range chains {
		if k, ok := replaced[c.File.Rel]; ok {
			c.Steps = []plan.Step{{Kind: k, Rule: reviewRule, Src: c.File.Path, Reason: "chosen in review"}}
			c.Warnings = nil
		}
		out[i] = c
	}
	return out
}

// 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
}