package main

import (
	"context"
	"fmt"
	"math"
	"strconv"
	"strings"

	stdio "git.novox.be/novox/mesh-sdk/go"
)

// Tools are the module's tools over one machine. Every one but zfs_snapshot only reads; zfs_snapshot only
// adds a snapshot. Nothing here destroys, rolls back, sets a property or sends: those change the
// operator's data and need a decision of their own.
func Tools(m *Machine) []stdio.Tool {
	ctx := context.Background()
	dataset := func(d string) map[string]any { return map[string]any{"type": "string", "description": d} }
	return []stdio.Tool{
		{
			Name: "zfs_datasets",
			Description: "Every ZFS filesystem and volume on this machine: name, mountpoint, used, available and referenced " +
				"(bytes), compression ratio, sharenfs, how many snapshots it has and the space they hold together " +
				"(usedbysnapshots: what destroying all of them would free), each in a line under `said`. A machine " +
				"without ZFS answers applicable false, with why. Replaces zfs list. (r)",
			Run: func(map[string]any) (any, error) { return m.DatasetsNow(ctx) },
		},
		{
			Name: "zfs_snapshots",
			Description: "The snapshots of one dataset (exactly that one, not its children), or of every dataset when none is " +
				"named, oldest first: name, creation time, used (the space only that snapshot holds: what destroying it " +
				"alone would free) and referenced. Replaces zfs list -t snapshot. (r)",
			Input: map[string]any{"dataset": dataset("the dataset, as zfs_datasets names it (optional: every snapshot when left out)")},
			Run:   func(a map[string]any) (any, error) { return m.SnapshotsOf(ctx, text(a, "dataset")) },
		},
		{
			Name: "zfs_snapshot",
			Description: "Take a snapshot dataset@name of one dataset, a person's act with why: refused for a dataset that is not " +
				"on this machine, a name with anything but letters, digits, '.', '_' and '-', a snapshot that already exists, " +
				"or no why. Only that dataset unless recursive is true, which snapshots every child at the same instant too. " +
				"Runs zfs snapshot -- dataset@name through sudo -n, then answers what zfs list shows: the snapshot made " +
				"and its creation time, and any other snapshot that came or went meanwhile. Recorded as the event " +
				"snapshot.taken; ZFS keeps it in the pool's history too. It adds a snapshot and changes nothing else. " +
				"Replaces zfs snapshot. (a)",
			Input: map[string]any{
				"dataset":   dataset("the dataset, as zfs_datasets names it"),
				"name":      map[string]any{"type": "string", "description": "the snapshot's name, after the @: letters, digits, '.', '_' and '-'"},
				"why":       map[string]any{"type": "string", "description": "why, in one line; kept with the act"},
				"recursive": map[string]any{"type": "boolean", "description": "true to snapshot every child dataset too (default false)"},
			},
			Run: func(a map[string]any) (any, error) {
				recursive, err := flag(a, "recursive")
				if err != nil {
					return nil, err
				}
				ans, err := m.TakeSnapshot(ctx, text(a, "dataset"), text(a, "name"), text(a, "why"), recursive)
				if err != nil {
					if _, absentHere := err.(errAbsent); absentHere {
						return NotApplicable{Applicable: false, Said: err.Error()}, nil
					}
					return nil, err
				}
				return ans, nil
			},
		},
		{
			Name: "zfs_pools",
			Description: "Every imported pool's health in a line: its state (ONLINE, DEGRADED, FAULTED, …) with status's own " +
				"explanation and action, size, allocated and free (bytes), capacity and fragmentation %, the error count of " +
				"its devices, its data errors and its last scan. Replaces zpool list and zpool status -x. (r)",
			Run: func(map[string]any) (any, error) { return m.PoolsNow(ctx) },
		},
		{
			Name: "zfs_space",
			Description: "Where the space goes: each pool's size, allocated, free, capacity % and fragmentation %; then every " +
				"dataset, biggest first, with what uses it (usedbydataset, usedbysnapshots, usedbychildren, " +
				"usedbyrefreservation), its quota, refquota, reservation and refreservation where set, the compression and " +
				"its ratio, the logical size against the physical and what compression saves. Replaces zfs list -o space " +
				"and zpool list -v. (r)",
			Run: func(map[string]any) (any, error) { return m.Space(ctx) },
		},
		{
			Name: "zfs_pool_layout",
			Description: "Each pool's layout as status gives it: its vdevs (mirror, raidz, draid) and their disks by the name the " +
				"pool knows them by (by-id where it was imported so), each with its state and its read, write and checksum " +
				"error counts and status's note (resilvering, was /dev/…); then the log, cache, special and dedup devices " +
				"and the spares. Replaces zpool status and zpool status -v. (r)",
			Run: func(map[string]any) (any, error) { return m.Layout(ctx) },
		},
		{
			Name: "zfs_scrub",
			Description: "Each pool's last scan, as status says it (ZFS keeps only the latest, a scrub's or a resilver's): when it " +
				"started and ended, how long it took, what it repaired and the errors it found, or, while one runs, its " +
				"progress and the time to go; and how many days since the last finished scrub, with a WARNING past 35. " +
				"With history true, also each pool's history (zpool history -i, as root through sudo -n) for the last " +
				"finished scrub and resilver status no longer shows; it can take some seconds on a pool with a long life. " +
				"Replaces zpool history -i. (r)",
			Input: map[string]any{"history": map[string]any{"type": "boolean", "description": "true to read each pool's history too (default false)"}},
			Run: func(a map[string]any) (any, error) {
				h, err := flag(a, "history")
				if err != nil {
					return nil, err
				}
				return m.Scrubs(ctx, h)
			},
		},
		{
			Name: "zfs_io",
			Description: "A sample of every pool's I/O over a few seconds (zpool iostat -v, the report since boot left out): " +
				"read and write operations per second and bytes per second per pool, vdev and device, with each " +
				"vdev's allocated and free. Replaces zpool iostat and zpool iostat -v. (r)",
			Input: map[string]any{"seconds": map[string]any{"type": "integer", "description": "how long to sample, in seconds (default 3, 1 to 10)"}},
			Run: func(a map[string]any) (any, error) {
				n, err := whole(a, "seconds", 3, 1, 10)
				if err != nil {
					return nil, err
				}
				return m.IO(ctx, n)
			},
		},
		{
			Name: "zfs_arc",
			Description: "The ARC, ZFS's cache in memory, since the machine started, from /proc/spl/kstat/zfs/arcstats: its " +
				"size, target, minimum and maximum (bytes), hits, misses and hit ratio %, the ratio for what was asked " +
				"for alone (not read ahead), and the L2ARC on a cache device where there is one. Replaces arcstat, " +
				"arc_summary and cat /proc/spl/kstat/zfs/arcstats. (r)",
			Run: func(map[string]any) (any, error) { return m.Arc() },
		},
		{
			Name: "zfs_events",
			Description: "ZFS's recent events, newest first, as root through sudo -n: by default only errors (I/O, checksum and " +
				"device errors) and changes of state (a device's state, a scrub or resilver started or finished, a pool " +
				"imported), each with its time, class, pool, device and state; all true gives every event. ZFS keeps " +
				"a bounded number since its module loaded. Replaces zpool events and zpool events -v. (r)",
			Input: map[string]any{
				"all":   map[string]any{"type": "boolean", "description": "true for every event, not only errors and changes of state (default false)"},
				"limit": map[string]any{"type": "integer", "description": "how many to show (default 50, at most 500)"},
			},
			Run: func(a map[string]any) (any, error) {
				all, err := flag(a, "all")
				if err != nil {
					return nil, err
				}
				n, err := whole(a, "limit", 50, 1, 500)
				if err != nil {
					return nil, err
				}
				return m.Events(ctx, all, n)
			},
		},
		{
			Name: "zfs_properties",
			Description: "Every property of one dataset with where its value comes from (local, default, inherited from …): " +
				"compression, recordsize, atime, sync, xattr, sharenfs, sharesmb, mountpoint, readonly, encryption, " +
				"keystatus, keyformat and encryptionroot and the rest, the usual ones said first in lines. Never a key: " +
				"keylocation's value is withheld. Replaces zfs get all. (r)",
			Input: map[string]any{"dataset": dataset("the dataset, as zfs_datasets names it")},
			Run:   func(a map[string]any) (any, error) { return m.PropertiesOf(ctx, text(a, "dataset")) },
		},
		{
			Name: "zfs_health",
			Description: "Whether this machine's ZFS is healthy, as the module's health check (novox/hq ADR 0240): unhealthy " +
				"when a pool is not ONLINE (with status's reason and action), a device has read, write or checksum " +
				"errors or is not online, a pool reports data errors, a pool is more than 90 % full, no pool is " +
				"imported, or ZFS is not on this machine; a pool more than 80 % full and a last scrub more than 35 " +
				"days ago are warnings, which leave it healthy. With why, one sentence per finding. (r)",
			Run: func(map[string]any) (any, error) { return m.Health(ctx), nil },
		},
	}
}

func text(a map[string]any, key string) string {
	s, _ := a[key].(string)
	return strings.TrimSpace(s)
}

// flag is a yes-or-no argument: true only when given as true; anything that is not a yes or a no is
// refused rather than read as no.
func flag(a map[string]any, key string) (bool, error) {
	switch v := a[key].(type) {
	case nil:
		return false, nil
	case bool:
		return v, nil
	case string:
		switch strings.ToLower(strings.TrimSpace(v)) {
		case "true":
			return true, nil
		case "false", "":
			return false, nil
		}
		return false, fmt.Errorf("%s is true or false, not %q", key, v)
	}
	return false, fmt.Errorf("%s is true or false", key)
}

// whole is a whole-number argument, defaulted, refused outside least..most.
func whole(a map[string]any, key string, fallback, least, most int) (int, error) {
	v, given := a[key]
	if !given || v == nil {
		return fallback, nil
	}
	var n int
	switch x := v.(type) {
	case float64:
		if x != math.Trunc(x) {
			return 0, fmt.Errorf("%s must be a whole number, not %v", key, x)
		}
		n = int(x)
	case string:
		i, err := strconv.Atoi(strings.TrimSpace(x))
		if err != nil {
			return 0, fmt.Errorf("%s must be a whole number, not %q", key, x)
		}
		n = i
	default:
		return 0, fmt.Errorf("%s must be a whole number", key)
	}
	if n < least || n > most {
		return 0, fmt.Errorf("%s must be from %d to %d, not %d", key, least, most, n)
	}
	return n, nil
}