package build

import (
	"encoding/json"
	"errors"
	"fmt"
	"slices"
	"sort"
	"strings"
	"time"

	occ "git.novox.be/novox/mesh-contracts/operator-and-conversation/go/clients/operatorchannelclient"
	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-sdk/buildstep"

	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-builder/builds"
)

// **builder_build answers a module's build keys whole** (design 47 G §589, A-87): with `fingerprint` that key whole, with
// `module` alone the module's keys newest first, at most MostBuilds, each with its fingerprint whole, its state, revision and
// since when, its step and node, its error whole, event-builds and the open ask (§568), and `newest` naming each watched branch
// whose newest catalog graph entry of the module names that fingerprint, read from the catalog half by the tools bundle.

// BuildTool is the builder's read tool of a module's build keys.
const BuildTool = "builder_build"

// MostBuilds is how many keys of a module builder_build answers by module alone.
const MostBuilds = 20

// BuildRow is one build key as builder_build answers it.
type BuildRow struct {
	Key         string    `json:"key"`
	Fingerprint string    `json:"fingerprint"`
	State       string    `json:"state"`
	Revision    uint64    `json:"revision,omitempty"`
	Since       time.Time `json:"since,omitzero"`
	Step        string    `json:"step,omitempty"`
	Node        string    `json:"node,omitempty"`
	Error       string    `json:"error,omitempty"`
	EventBuilds int       `json:"event-builds"`
	// Ask is the open ask of the operator about the key (§568).
	Ask *OpenAsk `json:"ask,omitempty"`
	// Newest names each watched branch whose newest catalog graph entry of the module names this fingerprint.
	Newest []string `json:"newest,omitempty"`
}

// OpenAsk is the ask the operator has not answered.
type OpenAsk struct {
	ID      string `json:"id"`
	Asked   string `json:"asked"`
	Expires string `json:"expires"`
}

// BuildAnswer is what builder_build answers.
type BuildAnswer struct {
	Module string     `json:"module"`
	Builds []BuildRow `json:"builds"`
	// Newest is the fingerprint of the module's newest catalog graph entry on each watched branch.
	Newest map[string]string `json:"newest-entries,omitempty"`
	// Note says what no key shows: that none of the keys is the newest entry's, naming its fingerprint.
	Note string `json:"note,omitempty"`
}

// BuildReader reads what builder_build answers.
type BuildReader struct {
	Builds StateRead
	// Entry is a key's value with its revision and when it was written; nil leaves both out.
	Entry func(key string) (json.RawMessage, uint64, time.Time, error)
	// Asked is the builder's state asked, which holds the asks the operator was asked.
	Asked StateRead
	// Newest is the fingerprint of the module's newest catalog graph entry on each watched branch, read from the catalog half.
	Newest func(module string) (map[string]string, error)
	Steps  StuckReader
	index  map[string]map[string]string
}

// Build answers for module, and for one fingerprint when fingerprint is not empty.
func (r *BuildReader) Build(module, fingerprint string) (BuildAnswer, error) {
	out := BuildAnswer{Module: module, Builds: []BuildRow{}}
	if module == "" {
		return out, errors.New("name the module (module)")
	}
	all, err := r.Builds.Keys()
	if err != nil {
		return out, err
	}
	var rows []BuildRow
	for _, key := range all {
		mod, fp, err := builds.ParseBuilderBuildKey(key)
		if err != nil || mod != module || (fingerprint != "" && fp != fingerprint) {
			continue
		}
		raw, rev, at, err := r.read(key)
		if err != nil {
			return out, fmt.Errorf("%s cannot be read: %w", key, err)
		}
		if raw == nil {
			continue
		}
		v, err := builds.DecodeBuilderBuild(raw)
		if err != nil {
			return out, fmt.Errorf("%s holds what is not a build: %w", key, err)
		}
		row := BuildRow{Key: key, Fingerprint: fp, State: v.State, Revision: rev, Since: at, Step: v.Step, Error: v.Error, EventBuilds: v.EventBuilds}
		if _, _, node, _, ok := builds.TransportFaultOf(v.Error); ok && node != "no node" {
			row.Node = node
		}
		if row.Node == "" && v.State == builds.BuildBuilding {
			row.Node = r.stepNode(v)
		}
		rows = append(rows, row)
	}
	if fingerprint != "" && len(rows) == 0 {
		return out, fmt.Errorf("the builder holds no build key of %s at %s", module, fingerprint)
	}
	sort.Slice(rows, func(i, j int) bool {
		if !rows[i].Since.Equal(rows[j].Since) {
			return rows[i].Since.After(rows[j].Since)
		}
		return rows[i].Key > rows[j].Key
	})
	if len(rows) > MostBuilds {
		rows = rows[:MostBuilds]
	}
	asks := r.openAsks()
	for i := range rows {
		rows[i].Ask = asks[rows[i].Key]
	}
	if r.Newest != nil {
		newest, err := r.Newest(module)
		if err != nil {
			return out, fmt.Errorf("the catalog half's newest entry of %s cannot be read: %w", module, err)
		}
		out.Newest = newest
		named := false
		for i := range rows {
			for branch, fp := range newest {
				if fp == rows[i].Fingerprint {
					rows[i].Newest, named = append(rows[i].Newest, branch), true
				}
			}
			slices.Sort(rows[i].Newest)
		}
		if !named && len(newest) > 0 {
			var says []string
			for branch, fp := range newest {
				says = append(says, branch+" names "+fp)
			}
			slices.Sort(says)
			out.Note = "no build key of " + module + " is the newest entry's: " + strings.Join(says, "; ")
		}
	}
	out.Builds = append(out.Builds, rows...)
	return out, nil
}

// stepNode is the node a building key's step runs on, read from its asks' steps in the build modules' steps; empty when none runs.
func (r *BuildReader) stepNode(v builds.BuilderBuild) string {
	if len(v.Asks) == 0 || len(r.Steps.Steps) == 0 {
		return ""
	}
	if r.index == nil {
		idx, _, err := r.Steps.stepIndex()
		if err != nil {
			return ""
		}
		r.index = idx
	}
	languages := make([]string, 0, len(v.Asks))
	for l := range v.Asks {
		languages = append(languages, l)
	}
	slices.Sort(languages)
	for _, l := range languages {
		bm, _ := buildstep.BuildSeat(l) // the steps are by build seat (StuckReader.Steps)
		st, ok := r.Steps.Steps[bm]
		k, found := r.index[bm][v.Asks[l]]
		if !ok || !found {
			continue
		}
		if raw, _, err := st.Get(k); err == nil && raw != nil {
			if step, err := buildstep.DecodeStep(raw); err == nil && step.Node != "" {
				return step.Node
			}
		}
	}
	return ""
}

func (r *BuildReader) read(key string) (json.RawMessage, uint64, time.Time, error) {
	if r.Entry != nil {
		return r.Entry(key)
	}
	raw, at, err := r.Builds.Get(key)
	return raw, 0, at, err
}

// openAsks are the asks kept in the state asked that nobody answered yet, by the key each is about.
func (r *BuildReader) openAsks() map[string]*OpenAsk {
	out := map[string]*OpenAsk{}
	if r.Asked.Keys == nil {
		return out
	}
	keys, err := r.Asked.Keys()
	if err != nil {
		return out
	}
	for _, k := range keys {
		raw, _, err := r.Asked.Get(k)
		if err != nil || raw == nil {
			continue
		}
		var kept occ.Kept
		if json.Unmarshal(raw, &kept) != nil || kept.Ended != "" || kept.Acted || kept.Ask.About == "" {
			continue
		}
		if t, err := occ.Time(kept.Ask.Expires); err == nil && !t.IsZero() && time.Now().After(t) {
			continue
		}
		out[kept.Ask.About] = &OpenAsk{ID: kept.Ask.ID, Asked: kept.Asked.UTC().Format(time.RFC3339), Expires: kept.Ask.Expires}
	}
	return out
}