// The .carlos/config file: a settable default console.
//
// Two levels, one shape. ~/.carlos/config is the machine's default;
// .carlos/config at a project root — committed to the repo — pins that
// project to a deployment (the titogo checkout says the Tito stack; a
// checkout with no opinion falls to the global). The nearest .carlos/config
// walking up from the working directory wins.
//
// A resolved default is authoritative: resolution never falls past it to
// "the only credential on this machine". Holding only a flagship credential
// inside a checkout pinned to another stack is an error naming that stack —
// never a quiet ship to the flagship. The single-credential convenience
// exists only for the no-default world.
//
// The file is deliberately not a secret and never holds one: nothing from
// ~/.carlos/credentials moves here, ever. It IS repo-controlled input when
// committed, which a malicious PR could repoint — accepted in the spec
// (docs/superpowers/specs/2026-08-04-console-default-resolution-design.md)
// because per-origin credentials mean no token ever crosses consoles, and
// every verb prints the console it is talking to.
//
// Destinations: one checkout can deploy to several stacks. A file may hold
// a "destinations" object of named blocks, each shaped like the top level
// (console, account, app, kind, artifact, target), and --destination / -d
// (or CARLOS_DESTINATION) picks one:
//
//	{"destinations": {"exciting": {"console": "...", "app": "shop"},
//	                  "tito":     {"console": "...", "app": "shop"}}}
//
// The chosen block is laid over the file's top level, so a key shared by
// every destination (say "artifact") can live once at the top. A
// top-level "default" names the block used when nothing is selected. See
// loadConfig for the resolution rules.
package main

import (
	"encoding/json"
	"errors"
	"fmt"
	"os"
	"path/filepath"
	"strings"
)

// defaultConsole is where `carlos auth login` lands when nothing — flag,
// env, project config, global config — names a console: the flagship. Login
// only; no other verb ever assumes it.
const defaultConsole = "https://platform.carlosframework.com"

// cliConfig is the whole file. Unknown fields are ignored on read and — since
// the account key landed — PRESERVED on rewrite (writeConfigKeys): the file
// is additive, other tools may learn to read it, and a rewrite that drops
// what it doesn't understand makes every future key lossy against the binary
// that predates it.
type cliConfig struct {
	Console string `json:"console"`
	Account string `json:"account"`
	// The project-defaults block (2026-08-13 spec): what this checkout
	// deploys as. App is honored by every app-scoped verb; Kind/Artifact/
	// Target answer zero-arg `carlos deploy`. All console-paired like
	// Account: a file's defaults mean THIS stack.
	App      string `json:"app"`
	Kind     string `json:"kind"`
	Artifact string `json:"artifact"`
	Target   string `json:"target"`
	// UpdateCheck: "off" disables the once-a-day newer-release hint
	// (update.go). Any other value — including absent — leaves it on.
	UpdateCheck string `json:"update_check"`
	// MessagePrompt: "off" suppresses the optional mutation-description
	// question. Any other value, including absent, leaves it enabled.
	MessagePrompt string `json:"message_prompt"`

	// Destination is the destinations block this view was resolved from
	// ("" when the file has none). Never read from or written to the file
	// as a key: it names what loadConfig did, for messages and the walk's
	// did-anything-define-it check.
	Destination string `json:"-"`
}

// configFile is the on-disk shape: the top level plus the named blocks.
// Blocks are cliConfig too, so a "destinations" key nested inside one is
// simply ignored rather than recursed into.
type configFile struct {
	cliConfig
	Default      string               `json:"default"`
	Destinations map[string]cliConfig `json:"destinations"`
}

// destinationFlag is --destination / -d, bound by consoleOption on every
// verb that talks to a console. A package variable rather than a value
// threaded through: the config is read deep inside session resolution, a
// long way from any flag set, and one process runs one verb.
var destinationFlag string

// selectedDestination is the destination this run asked for: the flag,
// else CARLOS_DESTINATION, else "" (let the files decide).
func selectedDestination() string {
	if d := strings.TrimSpace(destinationFlag); d != "" {
		return d
	}
	return strings.TrimSpace(os.Getenv("CARLOS_DESTINATION"))
}

// fileDefaultDestination is the block a file resolves to when nothing was
// selected: its "default", else its only block. names is never empty.
func fileDefaultDestination(path, def string, names []string) (string, error) {
	if def != "" {
		for _, n := range names {
			if n == def {
				return def, nil
			}
		}
		return "", fmt.Errorf("%s: the default destination %q is not one of its destinations (%s)",
			path, def, strings.Join(names, ", "))
	}
	if len(names) == 1 {
		return names[0], nil
	}
	return "", fmt.Errorf("%s defines several destinations (%s) and no default — pick one with --destination <name> (-d), set CARLOS_DESTINATION, or add \"default\": \"<name>\"",
		path, strings.Join(names, ", "))
}

func configMessagePrompt() (string, error) {
	cfg, _, err := walkConfig(func(c cliConfig) bool { return c.MessagePrompt != "" })
	return cfg.MessagePrompt, err
}

// walkConfig finds the nearest .carlos/config (cwd upward, then global)
// that pick() accepts, returning it with its path. The zero config and ""
// mean "no file said anything". Every per-key default walk (account, app,
// update_check) is this walk with a different pick.
//
// CARLOS_CONFIG, when set, skips this discovery entirely: the named file is
// the only one consulted, whether or not pick() accepts it. This is the
// override configDefault documents in the same terms as CARLOS_CREDENTIALS
// (auth.go credentialsPath) — for tests, and for anyone keeping their
// config somewhere other than $HOME's discovery path.
func walkConfig(pick func(cliConfig) bool) (cliConfig, string, error) {
	cfg, src, defined, err := walkConfigFiles(pick)
	if err != nil {
		return cliConfig{}, "", err
	}
	// A named destination that no file defines is a typo or a missing
	// block — never "no opinion". Falling through would hand the verb to
	// the single-credential convenience: a ship to whatever stack this
	// machine happens to be logged in to. Checked only when nothing was
	// picked, because only then was every file read: a stack key can only
	// be picked from a file that defines the destination anyway (loadConfig
	// strips it elsewhere), and a preference picked early says nothing
	// about the files past it.
	if d := selectedDestination(); d != "" && src == "" && !defined {
		return cliConfig{}, "", fmt.Errorf("no .carlos/config defines the destination %q", d)
	}
	return cfg, src, nil
}

// walkConfigFiles is walkConfig's discovery, also reporting whether any
// file it read defined the selected destination.
func walkConfigFiles(pick func(cliConfig) bool) (cfg cliConfig, src string, defined bool, err error) {
	visit := func(path string) (bool, error) {
		c, err := loadConfig(path)
		if err != nil {
			return false, err
		}
		if c.Destination != "" {
			defined = true
		}
		if pick(c) {
			cfg, src = c, path
			return true, nil
		}
		return false, nil
	}
	if p := os.Getenv("CARLOS_CONFIG"); p != "" {
		_, err := visit(p)
		return cfg, src, defined, err
	}
	if dir, werr := os.Getwd(); werr == nil {
		for {
			if done, err := visit(filepath.Join(dir, ".carlos", "config")); err != nil || done {
				return cfg, src, defined, err
			}
			parent := filepath.Dir(dir)
			if parent == dir {
				break
			}
			dir = parent
		}
	}
	path, perr := globalConfigPath()
	if perr != nil {
		return cfg, src, defined, nil
	}
	_, err = visit(path)
	return cfg, src, defined, err
}

// configApp resolves the configured default APP: the nearest file whose
// app key is set, with that same file's console for the pairing rule —
// exactly configAccount's contract, for the sibling key.
func configApp() (app, source, fileConsole string, err error) {
	cfg, src, err := walkConfig(func(c cliConfig) bool { return c.App != "" })
	if err != nil || src == "" {
		return "", "", "", err
	}
	return cfg.App, src, cfg.Console, nil
}

// configDestination names the destination block the configured console
// came from, when the session is using that console ("" otherwise: a
// --console to somewhere else is not "destination X").
func configDestination(console string) string {
	cfg, src, err := walkConfig(func(c cliConfig) bool { return c.Console != "" })
	if err != nil || src == "" || cfg.Console != console {
		return ""
	}
	return cfg.Destination
}

// configDeploy resolves the project's deploy block: the nearest file that
// names an artifact, whole — kind/artifact/target travel together, and
// mixing halves of two files would ship one project's bytes with
// another's shape.
func configDeploy() (cfg cliConfig, source string, err error) {
	return walkConfig(func(c cliConfig) bool { return c.Artifact != "" })
}

// loadConfig reads one .carlos/config whole. A missing file is a zero
// config, not an error. A file that cannot be parsed, or names a console
// normalizeConsole refuses, is an ERROR — silently ignoring a typo'd
// config would ship to the wrong console, the exact mistake this file
// exists to prevent. The console comes back normalized ("" when unset);
// the account comes back trimmed.
//
// A file with a "destinations" block resolves to one of them, laid over
// its top level:
//
//   - a destination was selected and the file defines it: that block;
//   - a destination was selected and the file does NOT define it: the
//     file's preferences only (update_check, message_prompt) — its
//     console/app/deploy keys describe some other stack. Same for a file
//     with no destinations block at all. walkConfig refuses when no file
//     defines the selection;
//   - nothing selected: the file's "default" (an error if it names no
//     block), else its only block;
//   - nothing selected, no default, several blocks: an error naming them.
//     Guessing, or quietly using the top level, is the wrong deployment
//     again.
func loadConfig(path string) (cliConfig, error) {
	raw, err := os.ReadFile(path)
	if errors.Is(err, os.ErrNotExist) {
		return cliConfig{}, nil
	}
	if err != nil {
		return cliConfig{}, err
	}
	var file configFile
	if err := json.Unmarshal(raw, &file); err != nil {
		return cliConfig{}, fmt.Errorf("%s is not readable as a carlos config: %w", path, err)
	}
	cfg := file.cliConfig
	if name := selectedDestination(); name != "" {
		if block, ok := file.Destinations[name]; ok {
			cfg = overlayDestination(cfg, block)
			cfg.Destination = name
		} else {
			cfg = cliConfig{UpdateCheck: cfg.UpdateCheck, MessagePrompt: cfg.MessagePrompt}
		}
	} else if len(file.Destinations) > 0 {
		name, err := fileDefaultDestination(path, strings.TrimSpace(file.Default), mapKeys(file.Destinations))
		if err != nil {
			return cliConfig{}, err
		}
		cfg = overlayDestination(cfg, file.Destinations[name])
		cfg.Destination = name
	}
	if strings.TrimSpace(cfg.Console) == "" {
		cfg.Console = ""
	} else {
		n, err := normalizeConsole(cfg.Console)
		if err != nil {
			return cliConfig{}, fmt.Errorf("%s: %w", path, err)
		}
		cfg.Console = n
	}
	cfg.Account = strings.TrimSpace(cfg.Account)
	// Same trim for every defaults key: {"app": "shop "} would otherwise
	// travel as shop%20 and 404 confusingly.
	cfg.App = strings.TrimSpace(cfg.App)
	cfg.Kind = strings.TrimSpace(cfg.Kind)
	cfg.Artifact = strings.TrimSpace(cfg.Artifact)
	cfg.Target = strings.TrimSpace(cfg.Target)
	return cfg, nil
}

// overlayDestination lays a destination block over the file's top level:
// every key the block sets wins. Preferences (update_check,
// message_prompt) are machine-wide in spirit and stay top-level only.
func overlayDestination(top, block cliConfig) cliConfig {
	for _, kv := range []struct {
		dst *string
		v   string
	}{
		{&top.Console, block.Console},
		{&top.Account, block.Account},
		{&top.App, block.App},
		{&top.Kind, block.Kind},
		{&top.Artifact, block.Artifact},
		{&top.Target, block.Target},
	} {
		if strings.TrimSpace(kv.v) != "" {
			*kv.dst = kv.v
		}
	}
	return top
}

// loadConfigFile is loadConfig's console-only view — the shape every
// console-default caller predating the account key still reads.
func loadConfigFile(path string) (string, error) {
	cfg, err := loadConfig(path)
	return cfg.Console, err
}

// configDefault resolves the configured default console: the nearest
// .carlos/config walking up from the working directory, else
// ~/.carlos/config. Returns the normalized console and the file it came
// from — the source goes into error messages, because "not logged in to X"
// is only actionable if you know WHICH file said X.
//
// If the walk passes through $HOME it finds ~/.carlos/config by the same
// rule — the global default arriving one step early, same answer. The
// explicit global check after the walk is for working directories outside
// $HOME entirely.
//
// CARLOS_CONFIG, when set, names the one file consulted and skips discovery
// entirely — walkConfig's override, since this is walkConfig picking on
// the console key.
func configDefault() (console, source string, err error) {
	cfg, src, err := walkConfig(func(c cliConfig) bool { return c.Console != "" })
	return cfg.Console, src, err
}

// configAccount resolves the configured default ACCOUNT: the nearest
// .carlos/config walking up from the working directory whose account key is
// set, else ~/.carlos/config. A level that names only a console does not
// stop this walk — console and account are separate defaults that happen to
// share a file. Returns the account, the file it came from, and that SAME
// file's console ("" when it names none): the pairing rule lives at the
// caller (apimode.go defaultAccount), which honors a file's account only
// for the console the file itself names — a config pair points at one
// stack, and --console to a different stack must not drag the other stack's
// account along.
func configAccount() (account, source, fileConsole string, err error) {
	cfg, src, err := walkConfig(func(c cliConfig) bool { return c.Account != "" })
	if err != nil || src == "" {
		return "", "", "", err
	}
	return cfg.Account, src, cfg.Console, nil
}

// globalConfigPath is ~/.carlos/config — the same directory that holds
// credentials, though this file is not a secret and never holds one.
func globalConfigPath() (string, error) {
	home, err := os.UserHomeDir()
	if err != nil {
		return "", fmt.Errorf("no home directory for ~/.carlos/config: %w", err)
	}
	return filepath.Join(home, ".carlos", "config"), nil
}

// saveConfigFile validates the console and writes the "console" key at
// path, preserving everything else the file holds (writeConfigKeys).
// dirPerm: 0700 for ~/.carlos, which MkdirAll leaves alone if it already
// exists; 0755 for a project directory that is meant to be committed.
func saveConfigFile(path, console string, dirPerm os.FileMode) error {
	n, err := normalizeConsole(console)
	if err != nil {
		return err
	}
	return writeConfigKeys(path, map[string]any{"console": n}, dirPerm)
}

// saveConfigAccount writes a console+account pair — the chooser's "save as
// this project's default" answer. The two keys land together deliberately:
// configAccount's pairing rule reads them as one fact ("this checkout means
// this account on this console"), so saving the account without pinning the
// console would leave a default that silently stops applying the day the
// directory's console default changes.
func saveConfigAccount(path, console, account string, dirPerm os.FileMode) error {
	n, err := normalizeConsole(console)
	if err != nil {
		return err
	}
	return writeConfigKeys(path, map[string]any{"console": n, "account": account}, dirPerm)
}

// writeConfigKeys rewrites path with the given keys set, keeping every
// field it does not understand — a rewrite that drops unknown keys makes
// every future config key lossy against the binary that predates it.
// Temp-file-then-rename like credentialFile.save, so a crash cannot leave
// a truncated config — but 0644, not 0600: this file is not a secret.
//
// Keys land where loadConfig would read them back: inside the selected
// destination's block (created if missing), else inside the file's
// default or only block, else at the top level. A file that cannot say
// which block is refused, as it is on read.
func writeConfigKeys(path string, set map[string]any, dirPerm os.FileMode) error {
	all, err := readConfigMap(path)
	if err != nil {
		return err
	}
	into, err := configWriteTarget(path, all)
	if err != nil {
		return err
	}
	for k, v := range set {
		into[k] = v
	}
	return writeConfigMap(path, all, dirPerm)
}

// readConfigMap reads a config as raw JSON, every key kept — the form a
// rewrite must start from. A missing file is an empty map.
func readConfigMap(path string) (map[string]any, error) {
	all := map[string]any{}
	raw, err := os.ReadFile(path)
	if errors.Is(err, os.ErrNotExist) {
		return all, nil
	}
	if err != nil {
		return nil, err
	}
	if err := json.Unmarshal(raw, &all); err != nil {
		return nil, fmt.Errorf("%s is not readable as a carlos config: %w", path, err)
	}
	if all == nil { // the file said null
		all = map[string]any{}
	}
	return all, nil
}

// writeConfigMap writes all to path, temp-file-then-rename (see
// writeConfigKeys).
func writeConfigMap(path string, all map[string]any, dirPerm os.FileMode) error {
	dir := filepath.Dir(path)
	if err := os.MkdirAll(dir, dirPerm); err != nil {
		return err
	}
	body, err := json.MarshalIndent(all, "", "  ")
	if err != nil {
		return err
	}
	body = append(body, '\n')
	tmp, err := os.CreateTemp(dir, ".config-*")
	if err != nil {
		return err
	}
	defer os.Remove(tmp.Name())
	if err := tmp.Chmod(0o644); err != nil {
		tmp.Close()
		return err
	}
	if _, err := tmp.Write(body); err != nil {
		tmp.Close()
		return err
	}
	if err := tmp.Close(); err != nil {
		return err
	}
	return os.Rename(tmp.Name(), path)
}

// configWriteTarget picks the object inside a parsed config that
// writeConfigKeys should set keys on — see its comment for the rule.
func configWriteTarget(path string, all map[string]any) (map[string]any, error) {
	var dests map[string]any
	if raw, ok := all["destinations"]; ok {
		if dests, ok = raw.(map[string]any); !ok {
			return nil, fmt.Errorf("%s: \"destinations\" is not an object", path)
		}
	}
	name := selectedDestination()
	if name == "" {
		if len(dests) == 0 {
			return all, nil
		}
		def, _ := all["default"].(string)
		var err error
		if name, err = fileDefaultDestination(path, strings.TrimSpace(def), mapKeys(dests)); err != nil {
			return nil, err
		}
	}
	if dests == nil {
		dests = map[string]any{}
		all["destinations"] = dests
	}
	block, ok := dests[name].(map[string]any)
	if !ok {
		if _, exists := dests[name]; exists {
			return nil, fmt.Errorf("%s: destination %q is not an object", path, name)
		}
		block = map[string]any{}
		dests[name] = block
	}
	return block, nil
}